Every once in a while, look for an evil tree to RS gold kill. They've a wonderful reward worth a little, then find a yew tree to cut down as you've got the auto-banking effect . You receive the auto-banking for some number of minutes based on how far you helped kill tree.
It's by no means the quickest route to 10M but it is stable and will get you eventually. A goal in this way is not easy since the temptation will be there to spend it on crap but to do it using one of my approaches: Require 10k and buy oak boards for -5% and see if you get some. The 10k is just a tester to find out if they buy and you ought to wait 5-10 minutes.
If they don't purchase then increase your bid 1-2gp till they do buy. Sell 1-2gp under centre cost. Generally you'll acquire 10-12gp for every oak plank (which usually means you ought to place your buy price at 13-17 under mid) you do which might not seem like much but the next time you will get longer, and more and more. . .before you know it you'll be trading 25,000 frequently and bringing in 300k each trade.
It is going to likely take you a week to achieve, but it is one of these things which may be done until the end of period; oak planks are absolutely stable in cost and so long as buy OSRS gold you never purchase too close to the middle price and never pay too much you will probably always profit.