Which upgrade to get?

I am a non-premium rank 8 player, and SP is not that easy to get. so i am mostly very careful where i spend my SP on. so i was hoping someone could give me a few tips on which upgrades to get first. i mostly play world maps, 3k 10k or 50k and whatever. my main strat is Sky Menace. i also use stealth ofcourse. here is my list of upgrades: http://imgur.com/a/RrP7M

if possible then i would appreciate if you could tell me in which order. for example the top 5 upgrades i need to get that i dont have yet.

Thanks

Imperialist
Guerilla warfare
Expendable ground main defence
Expendable ground stealth
Longer defence lines

Imperialist, Guerilla warfare, safer transportation, expendable ground main defense, lucky ground main defense.

Dont go for strategies rather than imp and gw since its not your type of gamestyle.

Go for main upgrades for inf and transportations.

Dont go for longer defense lines.It is a troll.