Well, since you have 75 thieving, go thieve from master farmers for some cash. Then if you want, get 99 mining via LRC after power mining 50-80 mining on iron ore.
I have a Skiller with 96 Thieving and 99 Fishing.
Don't really use it that often but I remember I made a lot from seed stealing at Master Farmers in Draynor or Rock Tail Fishing/Shark Fishing.