I was in your situation 2 months ago, all you need to do is bot coal at mining guild on like 3 accs for not even a week, and I guarantee you'll have your 10m.
Guys, you forgot about revenants. In f2p they don't drop ancient warrior shit but they can drop corrupt dragon, and if u hit the jackpots you'll get a corrupt scimmy (4m)
Chopping yews seems to be what everyone here does.
Give it a shot on a few accounts.
Or do a lesser money per hour method and bot 24/7 on multiple accounts.