a neat trick - if you're on a motorcycle (sports bike is the easiest for this) start doing a burnout then pull back to do a wheeley at the same time, if you turn while doing both of those, you can literally turn on a dime XD (I have had a lot of free time to play...)
quickest way to earn money (although not the safest) - once the allies and china get into the game, start killing one, i prefer going after the allies but over by the UP headquarters city... i don't remember the name of the city... you get 50k for each person and/or vehicle, if you get a helicopter (i prefer any of the ones sold by the pirates with the twin miniguns) you can easily destroy their humvees and men on foot
Multiple pick-ups by helicopter pilot - if you "tag" multiple pick-ups then throw the smoke grenade he will only hook on to one but they will all be collected at the same time... saves alot of your time XD
by the way, i have gotten 97% complete O.o... which is weird because i've gotten OVER 100 of the spare parts and i've completed all missions and all the HVT's and destroyed all the targets... the only thing i can't do i a couple of side missions which, i'm guessing, unlock a couple more vehicles. Like the ones where you deliver the proto-type boat to the chinese from the P.L.A.V. i think... and the one where you drive a chinese tank through allied controlled road-blocks... those are the only ones i havn't done... and now that i've completed the game i can't do them so, if you're trying to get 100% you have to do them before you do the 3rd mission for either the allies or chinese... speaking of which the chinese 3rd mission was way too hard for me... i ended up going through the allies missions on both of the games i completed... there's is nothing compared to trying to destroy those four buildings for the chinese...
anyways, that's all for now