Your top goal in any Zombies game, even if you're playing solo, should be to earn points by fulfilling contracts. Certain contracts in Modern Warfare 3 Zombies will be much easier to complete on solo than others. So in this guide, we’ll share some of the best contract to carry out in MW3.
The first one being Raid Weapon Stash - This contract merely requires you to wait for the time to reach 100%. It has the potential to drop you a weapon that is rarer than the one in your loadout, which is something you will want to. As long as you're close to the stash- safe, you don't even need to be in the same room as it. You can get that by just killing the occasional zombie, and when you do, you'll undoubtedly acquire a weapon that is rarer than your loadout and will therefore deal more damage.
Deliver Cargo is the next contract; it's a fairly easy one that has you simply driving a car from one area of the map to another. This is also an excellent way to explore other areas of the map, as it guarantees a vehicle even in the absence of any others.
Eliminate The Bounty contracts are also excellent to complete on Solo. A green rarity weapon is a must at this stage in the game, so you can do a little bit more damage to the Elite bosses to finish these contracts faster.
The last contract is The Outlaw, which is likewise quite easy to complete and plays a lot like the Raid Weapon Stash. All you have to do is kill some zombies and wait for the timer to reach 100% to be finished.
It is recommended that you complete contracts in the low threat zone until you have approximately 15,000 points. The Reward Rift should provide you with some respectable goodies during this time along with some free perks and maybe some EA wrenches to upgrade the rarity of your weapon. However, if you happen to find a Pack-A-Punch Crystal, save it for later use; don't use it right away.