Become a merchant, buy for cheap guild wars gold, sell for lots.  Of the games, Prophecies is very general, Factions is geared towards PvP and Nightfall is geared towards PvE; for some this one factor makes up their mind. Choose how much time and effort you want to put into skill and gear collection. Running/map exploration/helping newbies/learning the games lore, go back to old places and help other people or explore areas you missed, learn to run past enemies and help other players by running them past hard areas, talk to NPCs you missed and learn the lore behind the game.

Help your guildies rock as much guild wars gold as you.And if you did all that stuff, then you might want to think of taking a shower, because you have probably been playing since prophecies release without moving from your chair. There are a lot of people who want to get rid of their crap or dont know how much thier items are worth, buy their stuff for really cheap, then sell other stuff to them for very high prices. If you end up with two much guild wars gold, buy koss some 15k armor, give the guild wars gold to a newbie, or find some other revenues to get rid of the guild wars gold.

Make your heroes as good as you, because youre going to have like 10 of them per character, and they all need weapons and armor and pets! Hehe, I went and got a black moa bird for all my heroes, and now when I do missions with 3 heroes I make all of us secondary ranger and bring my black moa squad, very fun.