A couple small tips to farm gold:
1) use trials of bots before purchasing, think outside of the box.
2) Instead of thinking I will farm f2p yews (insta ban imo) or picking flax, red chins or green dragons (what most people thing of bots) think about something very unique like making jewellery for profit (rings of recoil etc) A skill which normally costs to level but has one or two small profitable skills.
3) Put some money into to see a honest return - do not try to start with nothing (all f2p bots) , a lot of people will say start small 1-2 accounts - which is ok, I however think to start set up a budget. If you can to afford to lose $50 go for it - great fun but be realistic if your farm gets hit you should have enough cash to rebuild - fresh proxies / accounts with members.
4) Always sell to trusted sellers, R2 is good - rates are low but you know you aint going to be stuffed around.
Good Luck.