Well I started my guild(SHRUB,~190 hours atm) before guilds were even out and made it when the official system came out so idk.
I'd say gather a large group of friends and take a tower(mod when its changing is easiest). Once you get a tower many people will ash to join while you own it. Tecruit them, many will leave after its lost but some will stay. Have ranks as a source of inspiration for participating.