Welcome to Menewsha. :)

You can, as said, make gold in the arcade or by posting in the forums - the longer your post, the more gold you get, so the RP forum is a good place, as is the Literature Spot forum - as well as by joining contests (that is, if you win), getting chosen as Admin's Pick, filling application form at a charity, get some random gold there or win a pageprize there (or anywhere else, but it seems the charities have most pageprizes), selling art, donating to Mene and sell the items you get for it, use some gold (once you've build up a nice stack) to buy items in the exchange that are popular, wait a while and sell them when they're worth more, etc.

Most things are fine, as long as they have nothing to do with begging, bumping/spamming/trolling/flaming, hacking (whether a person or the games)/scamming or off-site trading, I guess. Not that I think you'd do that. xD