Well NCJohn, Gamelova and Froggy have all inspired me to make my own guide. This guide will teach or refresh your minds on how to take, defend and general tips when Basing. Hopefully your gang might get a few more hours!

Firstly, lets start with the basics. There are 7 current bases on iEra they are:
Lethal Securities
Blackholst Zone
Mafia Zone
Blazin Bandits Zone
Tachi Zone
Gangster Zone
E-Mines

Here are some general rules to follow at every base when attacking:
1. NEVER go straight towards the flag and start attacking. It results in the defender(s) getting some easy shooting practice at your head. This rule applies for MOST bases (see Lethal Securities notes)
2. I know its the nice thing to do, but when entering a base, don't just let other attackers walk alongside you. Kill them before they kill you.
3.Be aggressive. For some people this is a hard thing to do but when attacking don't run from the defenders/other attackers. Show them you WANT the base.

Here are some general rules to follow at every base when defending:
1. Work together with your gang. Your gang message button is there for a reason USE IT!. If you follow this rule your almost guaranteed to keep the base.
2. Observe the attackers habits. I find this quite handy. If someone is entering through the same entrance all the time, shoot in that direction. You can get them down a lot on their healthbar then finish them.
3. Use items. Use items such as P4's, mines, bear traps (highly reccommended), boxes/crates (highly reccommended), etc.

Also, these are some good techniques commonly used in the spar arena, but also work nicely when basing:
http://www.graalians.com/forums/showthread.php?t=2678

Now lets focus on individual bases:

Lethal Secrurities:

Ah, Lethal. The home of PK. The key to take or defend this base is to avoid PKers on the roof and have a fast iDevice ;). Lethal can go from being empty to being so packed you can't see your own character within 3.5 minutes SO WATCH OUT! All types of gangs come to Lethal but normally new gangs normally come to lethal looking for some quick, easy base time.

Attacking:
-An exception to my previous rule, in some cases it is neccessary to go straight at the flag and attack it. This works really well with a fast melee weapon such as a hunter, kiwi, pitchfork, etc.

Defending:
-Making a wall, across the flag with a couple gang members and shooting across seems to work. Especially if you have a gun like Shipka, PBP Shotgun.
-Going on the seat closest to the flag and shooting up and down (depending on where attackers are entering) seems to kill, or at least damage the attackers.

Blackholst Zone:

Blackholst Zone, possibly the place where most people took there first base? Overall it is a great base, and over time many gangs have called it there 'home base'. So what has this base really got to offer?

Attacking:
-Tell your gang members to enter different sides and shoot accross. This makes the defenders have to come between your line of bullets from each side. And if they don't? Eventually you will take the base because the some of the bullets will be hitting the flag, lowering it down...
-When you get a clear chance, run down and sit on the chairs in the flag room and shoot up. Not only do you kill the defenders and incoming attckers, but you also get a clear shooting target at the flag.
-If the defenders are doing the tip above. Simply frag grenade them from the seats just outside the flag room then they will have to move from there spot.

Defending:
-Tell your gang members to sit on the chairs in the flag room and shoot up. You have no idea how many kills you will get. I got a 50 streak from doing it once
-Get 2 gang members with the best melee weapons to stay on the doors before the flag room and constantly hit it. As nooby as it is, it works...
-Send at least 1 gang member outside the flag room.

Mafia Zone

Pay Day! Mafia is possibly the best paying base in iEra and it is quite often packed with attackers. Once known as 'Ebizou territory' is now open for other gangs to fight over. However, there are many techniques to this little base that come in handy...

Attacking:
-Shoot up. When you enter the room before the flag room, shoot up. Normally the shorter door is open and your bullets will carry through and wipe out the defenders/other attackers.
-Send your gang members to attack through the long way occassionally. I see lots of people go through the shorter way and get killed. So while other attackers do this, go the long way and shoot across the flag room.

Defending:
-Stay outside the flag. I see gangs like 'I Luv Haterz' doing it a lot, they sit right outside the flag so no one can even get near taking the base.
-Like Blackholst, get 2 gang members with the best melee weapons to stay on the doors before the flag room and constantly hit it.

Blazin Bandits Zone:

One of iEra's favourite bases. Many people like its layout, others like its colour and I had one Player tell me he liked its name? Knights of Honor used this base to launch themselves on the top of the gang base scores. So how did they manage to keep top gangs like Ebizou away? I'll tell you how.

Attacking:
-When your about to walk past the flag, shoot down. Normally defenders do this except they shoot up to stop attackers from going near the flag. So shoot down early to get the upper hand on them.
-Use the big table in the center to avoid there attack. Use it to avoid there attack, and when they follow you, turn shoot them and run away from there bullets. Repeat the process to you kill them.

Defending:
-Send gang members outside (the room where there are seats across the bottom and a glass panel)
-Have 2 people on doors. Like the last 2 bases.
-Have 2 people shoot up. Stops attackers from going near flag.
-Like the attackers, don't be afraid to use the table to your advantage

Tachi Zone:

Another popular base among iEra players, Tachi has lots to offer. With its wide flag room, there is a constant battle, dodging, rushing. So what SHOULD you be doing at Tachi to archieve more base hours?

Attacking:
-Send 2 people to go the long way (the door further away) and shoot across the flag room together. This generates a wall of bullets that the defenders can't avoid.
-When you enter the room before the flagroom (the room where you must destroy the doors) shoot up. This results in you opening the door, shooting up and killing half the defenders who didn't expect it.
-A tecnique that I see Vince Gohshucks doing all the time is shooting through the little wall in between the 2 doors. By shooting across there you are likely to kill many people who try to block and defend the door.

Defending:
-Stay in a place where you can't get hit and wait for the attackers and basically use Froggys dodging technique to keep the base.
-As usual, get 2 gang members with the best melee weapons to stay on the doors before the flag room and constantly hit it.

Gangster Zone:

Did someone say GZ? Gangster Zone aka Terisu Base is my personal favourite. The secret entrances and shortcuts are just some of GZ's benefits. Many people including myself love the bank entrance and shooting up and killing defenders or attackers.

Attacking:
-In the room before the flag room, there are normally defenders waiting for you so be prepared...
-When entering through the bank machine way, shoot up. Not only are you hitting the flag but you get an average of 3.65874 kills everytime you do it.
-Approach GZ in packs (2 or more members together) this helps a lot with the killing process.

Defending:
-Keep at least 1 gang member outside the flag. This kills or at least weakens the attackers.
-Take shifts. By this I mean someone stays outside the flag kills the attackers. Goes back inside the flag and heals while another gang member who was already inside the flag goes outside and replaces him/her/shim until the original gang member outside the flag is ready to return and repeat the process.

E-Mines:

The new base on iEra, has only been out for a little while, but has already become one of iEra's favourites with its stunning layout, hidden secrets and unique style.

Attacking:
-Use the structure of where the walls are to your advantage. In the room before the flag there are walls zig-zaged everywhere. Confuse the defenders and use dodging techniques to overcome them.
-When in the flag room bring a friend. Split up one go the top way the other go the bottom way and surround the defenders with bullets.

Defending:
-Stay outside the flag room. It works for this base really nicely.
-Take shifts (read GZ for info)

Thanks you for bothering to read all of this. I hope I taught you something!
Please let me know what you all think.
NOTE: I will edit this regularly, fixing spelling and punctuation, adding screenshots, etc  

Very nice guide, my only suggestion is that maybe next time add some colors or pictures to make it a bit less bland.  

Yer, I will edit in hopefully some screenshots tonight.  

Good Guide.  

Posted by NCJohn

Very nice guide, my only suggestion is that maybe next time add some colors or pictures to make it a bit less bland.

Exactly.

Got bored in the end of Lethal  

Brilliant suggestions, it'll be interesting if people will put this to good use. + Rep great job !  

Thank you everyone. Taking some dodgy screenshots now ;)  

Nice.. It kinda helped me  

Hehehe, can't wait for the screen shots
I'd +Rep you but I can't  

Love the guide its spectacular! Did I hear GZ is your personal favorite ;)?  

Not to be a buzzkill, but in gz if you only have one outside the flagroom you will lose the base, you need to have one in flagroom and the rest outside it.  

Posted by DMG

Not to be a buzzkill, but in gz if you only have one outside the flagroom you will lose the base, you need to have one in flagroom and the rest outside it.

Posted by Thunderstorm

-Keep at least 1 gang member outside the flag. This kills or at least weakens the attackers.

Posted by Vince Gohshuks

Love the guide its spectacular! Did I hear GZ is your personal favorite ;)?

You sure did  

I think it will really help people on IEra well done  

What happened to adding some screen shots.  

Ah, good question Vince.
I took the screenshots on the same day of the original post. But I dont know how to insert them without attaching the image.
It says enter the URL of the file, but the pictures are not on any website. Lol