Personally out of all of the Veteran achievements for this game, I found this to be the second easiest (first being Semper Fi). The reason being is that a lot of the action, your dealing with from a distance - but don't let that fool you into thinking you cannot be killed from a distance.
First of all you shouldn't have any trouble with the sniping at the beginning of the level. When you have to get rid of the sniper - be aware that he can and will kill you with one shot if he hits you - dispose of him as you would normally but with extra care. When you get into the building which get's torched with you inside - you must stay on the floor until you get to just after the bookcase falls. Make sure you take out the two guards at the windows that will more than likely kill you with one hit if you don't deal with them.
After that some sniping skills will need to be put to use - make sure that you stay well covered and try to snipe from even further back instead of directly behind the front wall (where they will expect you to be). Take out the ones that matter (EG MG'ers, tank turrets and ones that theaten you from a higher position). After that you will need to deal with a few people on your level but grab an SMG to deal with them (watch out for the dogs also).
Then yet more sniping, keep well back and concealed - only popping up to take a shot or catch a quick glimpse of where the enemies are - keep in mind the tactics that you used in the first sniping bout.
Again, more guards that will try to take you out from your level. SMG them but make sure you have a vantage point (at the top of the stairs for example) so you can pick them off as they come to you.
The penultimate part see's you try to kill General Amsal with a sniper rifle. Take your time, learn when and where he moves to, take out any other enemies that pose as a threat (the initial sniper when Amsel appears and the two snipers after). If you shoot the driver that attempts to drive Amsel to safety you can buy yourself a few seconds to get a decent shot. I only shot him twice but other's have said he takes more to kill.
When you have finished that make a mad dash to the end of the level - ignoring the guards coming up the stairs - reznov will deal with them.