i usually follow those rules:
1) place all traps and teslas
2) upgrade critical buildings (spell factories, lab, camps and cc)
3) place all regular defenses (not xbow, infernos, eagle)
4) start pushing heroes - get them to 20/20 for solid attacks
5) upgrade troops in lab and in the meantime start working on point defenses
6) when point defenses maxed, move to wizards and one by one place buildings left out in #3.

good luck