What i think you should do is this:
1. Upgrade +2 gold per second and miners (either upgrade)
2. Upgrade the +100% health for your monument
3. When you can, get your swordsman upgrades.
4. Keep upgrading the economy (+2 per second and miners)
5. Then start upgrading your speartons.
6. Upgrade the sumon +1 minions on your magikills (when hey are unlocked)
7. Keep upgrading the previous except magikill.
8. When you can, upgrade you giants.
9. Keep upgrading the previous excepty for magikill and giants.
I usually get a miner (or two) at the start of every level, then just get swordwraths. I almost never get archers. My 2nd favourite is a controlled spearton, then a giant, then a magikill.
I hope that helped
thanks