It's a boosting solution because it seems to be nobody playing non private matches...
4 player private match 2 bots(hard diff. - not finishing task) - friendly fire ON!!!!
with 2 people(including you) just switch both of you to medic and call a supply crate for your teammate and start shooting next to his/her crate. It will deplets the crate very fast about 2.5 minute later you and your friend have 2 medic star which is the fastest way to get the 100 star.
This method will complete the 100 supply crates as well!
The last is the 250 healt pack given - if you are a medic, your teammate swith to field ops. You shoot him and heal him with your medkits....and he will be dropping you ammo crates wich it helps him another achivements(where needs to get fieldops stars and throwing ammo packs)
sorry for my english:) tried to do my best...