since you're ftp there isn't too much you can do, but here's a start.
melee/ranged combat: kill moss giants or hill giants, bank the big bones and sell.
magic: no idea if you can make a profit with magic in non members >_>
mining/smithing. steel bars or raw materials is the only way really in non members.
you can buy or mine the supplies for steel bars, you make profit regardless, if you mine it obviously you get more money overall. plus if you mine all your coal and iron, you'll get some chances to mine some mithril, which sells at like 450 each last i checked.
runner skills: mining/fishing:
for mining, its gold, for fishing, its lobsters. for this you need to hire a runner to bank your ore/fish for you. camp the crafting guild/fishing platform and collect your inventory of 26. you then sell these to your runner at a discounted price, and they then bank it and come back for more. if they walk, they usually get back from the closest bank about the same time you finish your next load. in free worlds, its good to just give the 3k discount.with lobsters, 26 lobsters is currently 8700 gp approximately, so 6-7k would be good. and in f2p. most players would be glad to make 2k for doing almost nothing
for gold, you get more cash per load, but its harder to mine it fast unless you're a higher level. but even if they take out the full 3k from it, you're still getting 9k per load. not bad eh? although at 55 mining gold can be hard, so i wouldn't reccomend it until you're at least 65 mining.
lastly: wcing. mine yews.
