On the Imp side I have 12 toons, three are in a large guild, the other nine are in a guild created by myself, for myself. I use the second guild (with bank), to support the 3 mains on Imp side, as crafting/gathering minions.
Extra cash is in the bank, and mats etc dropped from missions, are also put in the bank, so when I log an alt who can use the stuff they can take from the bank and deposit other gear for other alts etc, and deposit cash.
So if any of the crafting toons need mats, they can go to the bank, or need cash they can withdraw it etc, also handy is all cash kept in one spot, if I level some of the alts, they can use repair funds set up by myself.
Another thing was if an alt found something decent on the GTN, but had no cash, problem solved race over to the guildbank. Hope that helps.