here is my way : first, buy the 1st ship upgrade, then, buy the 4th and 3rd loot and magnet, collect money till you can buy the 4th weapon and the 2nd ship upgrade, sell the 3rd loot and magnet and buy the 4th flag, and then continue till you can buy 4th fire rate and 3rd flag
i actually found a bug, clear the data of ur character when u r using one of the *200 GP to activate*, then when u load ur new character, u'll still have that *200 GP to active* activated!