Try the Grand Exchange in world 2.
Any one of the Main trading worlds.
The Wilderness.
Fishing guide
The best place to kill zombies is at the armor zombie place. IT is where everyone get 99 str.
You can find information about the best place to invest funds on Wikipedia or on investment trading platforms like Etoro, Binary Options trading, and Forex Trading.
Trading RuneScape accounts is against the terms of service of RuneScape, so just build up your own account. If you buy a account, they will hack it back later at some point as they will have all history of account and you will be helpless as you will be losing real money for it. There are lots of websites which sells them but avoid them all.
Living Rock Caverns
stronghold of secutity i like
grand exchange.
barb village
Killing Fire Giants at Baxtorian Falls is a great place for training.
The best place to find cursors is to do a search through google.