Minecraft wiki entry for Multiplayer_PvP_bases, associated text: Branch out your mine and hoard all that precious iron and diamond.
Make an experience farm or grinder.
Sell the spare stuff you don't need instead of letting it clog up your storage space.
Create a faction armory with at least 1 reserved set of armor and weapons for each member.
Get resources from the Nether such as blaze rods or quartz.
Recruit people into your faction to speed the process up as well as improve defensibility
Pick a side in whatever is the large conflict is to gain stronger allies and to have someone to fight.
Expand your farms to become self-sufficient.