@Walli
FYI, cannon doesn't recognize mage bonuses when it comes to working out how often/how hard you hit with cannon. So don't mage while cannoning basically.
Most cost-effective way to train would be to use rune arrows + msb. They're dirt cheap - particularly at the moment with the BH update. I wouldn't bother cannoning if you're skint.
I'd get f cape before I even start on str honestly. Also don't know what wep you're using but since you shouldn't have finished MM you should be using a viggora's chainmace without ether in it, since it's identical str bonuses to d scim. Anything else and you're wasting your time. I assume you don't even have a B ring yet either.
Check out my guide to maxing fast. Ofc a lot of the things cost a lot so just take what you want from it...
Also you could maybe use a crossbow and a tome of fire and alch between hits with autoretaliate on. You can see a list of profitable alchs on "alchmate" - not sure if I can link it here so won't try. That way you can build up a cash stack, while training range, and getting your mage up at the same time. Some of the best alchs are those that bring up a warning, but I think you can change your alch warning to place it higher, meaning that you can alch without the warning for high margin items (ofc you need a good starting stack to begin with to do this). Dhides are the cheapest, followed by some battlestaves IIRC.
Set up the hotkeys on your keyboard so you can literally just hit the 5 key to alch while not looking at the screen.
GL with the account (y)