There are 5 attributes in the game:
Health (1 Point = 5 Health)
Stamina (2 Points = 1 Stamina)
Your energy can stack to an indefinite amount! Do not put ANY points into Energy; after adding 200+ allies you should have power-ups being sent to you daily. Use those energy drinks! They stack! If you use an energy drink and it gives you +40 energy while you are at 10/10 energy, you will have 50/10 energy. Your energy can stack to an indefinite amount! You can have 99999/10 energy and more. The same applies to ammo. Ammo is useful for players who rely on bounties or invasions to obtain money or gold bars.
Attack and Defense attributes may not look like they make a large difference in battle while you are at a lower level, but they make a large difference at higher levels (80+). This is because of the 3/7 tactic set-up that most players use (see Tactics page).The 3/7 set up will suppress the power of your enemies' weapons and vehicles by 98%, so these attribute points are very important.
There are players who will be able to defeat you even if you have maxed out 3/7 and they do not. You may max out 3/7, but have all of your attributes in attack. Your opponent may have all of his attributes put into attack as well, so that when he or she attacks you they will win, because their attributes for attack will be higher than your defense attribute.
You can reallocate your attribute points by visiting the black market. Be warned: The first time you reallocate your attribute points it will only cost you 10 gold bars, but any time you reallocate after that it will cost you 40.