In this game, you can use lots of cheats and I'll be very glad if you will find the following ones useful for you!
To get Higher rank, make the following procedure. Note that you have to edit a game file to enable the cheat, so make a backup copy of this file first before editing it. Well, go to the \battlefield 2142\profiles\0001 directory and find there the profile.con file. Then, open it in any text editor such as NotePad. Find the following lines:
LocalProfile.setName "user"
LocalProfile.setGamespyNick "user"
LocalProfile.setEAOnlineMasterAccount "user"
LocalProfile.setEAOnlineSubAccount "user"
LocalProfile.setTotalPlayedTime 25467.3
LocalProfile.setNumTimesLoggedIn 9805
LocalProfile.setRank 0
LocalProfile.setCareerPoints 0
LocalProfile.setLastBaseUpdate 0
Now, when you got it, choose the lines
localprofile.setRank 0
LocalProfile.setCareerPoints 0
and set the values 43 and 54100 in this order.
To unlock Dogtagger Dagger knife reskin, do the following:
All you need is to obtain 50 unique Dog Tags on your soldier's account and yiu will get the Dogtagger Dagger knife reskin unlocked.
To make Heal faster, you can do this trick:
When you are playing as the Assault class, try to throw one medkit on the ground and hold one in your hands to heal twice as fast.
How to fight enemies:
If your enemy's Titan shields are down, you have to attack it. The enemies will be waiting for a while, but still you must attack the core because this will help you succeed faster. One more comment: use teamwork to get the desired result for sure.