No matter what level you are there are always way to make money in the world of RuneScape.
Woodcutting
One of the most popular ways to make money is Woodcutting. Even if you just started you can still make a fair bit of money. Start of by cutting Regular trees and banking for 30gp each. This will give you enough for you noob armor and stuff smile
Continue this for what seems like forever. Once you get up high enough then you should start cutting yews.
After yews there is the money maker. Magics.
Fletching
This way of making money involves you to have start off money or will take a long time. Get 65 Fletching and buy unstrung yew long bows. String them by making strings or buying strings (if you buy it will double your money).
Flax
Pick flax in an area (preferabley Camelot) and then go to lumbridge castle. On the 2nd floor there will be a Wheel that can turn your flax into Strings. Sell the strings.


There are many other ways to make money just look through the game smile