Lower the difficulty for the first levels, otherwise it's too difficult from the start
This game only needs 5 steps that can be repeated for all girls.
1. Get a turret.
2. Focus on bed and door as needed. Try to keep door at same level as monster.
3. Keep highest turret at same level as monster at minimum. Add 2nd turret no later than monster level 3.
4. When 1st turret is level 3-5 add the booster; upgrade as needed, but no need for closer than 2-3 levels of highest turret until bed level 10.
5. Win