Great guide, I have a few more tips to add.
1. Save a UAV and let your team know you have one on hold. When they get an airstrike they'll be glad you did.
2. Ask everyone on your team to put bullets into the chopper. If 2 or 3 people do this it goes down fast and makes the other team angry
3. Don't use stopping power just for juggy users. Its even more effective vs the other 80% of players who don't use jugs.
4. Stay out of doorways and bottleneck areas. Don't wait to hear one of your teammates swiping you with a knife before you move out of their way.
5. If you see someone out of the corner of your eye don't try and turn to face them, go around the corner, crouch, aim, and kill them when they come after you thinking you didn't see them.
6. As you traverse the map and come across another gun lying on the ground, don't be scared to drop you pistol and pick it up. This has saved me countless numbers of times.
7. Learn to knife, let it become 2nd nature so that you don't even have to think about doing it. When I first started playing this was something I rarely tried. Now I do it without even thinking about it.
8. You just killed a guy with martydom, he drops his nade, what do you do? You pick it up and chuck it, thats right, stop complaining about marty users and learn how to counter them. Practice with a few friends in a private match until you get the timing down pat. In no time at all you'll see the marty users just give you an extra grenade. Of course if the situation calls for a quick exit, by all means run. But you'll be surprised at the number of kills you'll get with a marty nade.
9. If your just getting into HC games, do not rush around. This game is hard enough in normal to rush around and not check corners. But in HC its a must to watch those corners.
10. Communication, communication, communication...need I say more?