Hello there!
I'd suggest doing slayer its good money making doing upon completing slayer task you have a chance on receiving slayer key
The key goes for around 15-20m
Also you can try ::starterboss as well for some good money making for new players
Join events they host them from time to time!
Also do ::ref select youtuber and type eggy for a first purchase package which contains dream range set bfg900 main hand and helicopter pet
All i have to say good luck!