When you first start playing SoulPlay, the best option to start making money is thieving. Granting up to 18,000 coins per click. You will find a row of thieving stalls directly on the north wall of Edgeville bank. Thieving from the highest money making stall can earn around 20m per hour.
Once you have trained your combat skills up to level 100+ you can attempt Player VS Monster AKA PvM. You can choose monsters like Abyssal Demon's or Steel Dragon's or even Iron Dragon's. You can kill them for bones and sell them for up to 150k each. Frost dragons however drop bones that sell for 500k-600k each. It is recommended to use a Dwarf Cannon when engaging with Frost dragons for the most efficient kills. Abyssal Demon's are popular for their drops for Abbysal Whip's and Dragonstone's, as well as key half's and coins.
If you are a fan of PVP. You can fight other players in the wilderness, use the clan chat to find someone that will 1v1 with you. Or go to duel arena and risk cash and items if you're a PVP type of person. Talk to Scrambles Infront of The Wilderness to buy PK Equipment to begin Player VS Player, If you Defeat your targets, you have a chance to Retrieve Valuable Items!