Knowing when to retreat is a very useful trick. It does not mean you are a "pansy" or "noob" it is merely thinking smart. If you end up in a one on one, or even one on two fire fight and your clip does not finish off the enemy, make a tactical retreat. This gives you the opportunity to drop grenades so the enemy cannot advance further upon your position, or even find cover further back and make flanking fire to drawn out mercenaries. This tactic also works as bait, to lure enemies into a set "killzone".

Dropping a nade buys you time usually. But alternatively, you can cook a nade, wait for them to turn the corner, and kill one or even a group, instantly.

You have to make your choice carefully. Ive gotten into trouble by cooking instead of dropping and reloading, but its also rewarded me plenty. If you are confident in your side arm, you could try to cook and then swap to sidearm. Its a risk vs reward, but nothing is more rewarding than slowly taking out an entire squad, one at a time, via these types of guerilla tactics as they chase you down.

Widdling their numbers down from 5 or 6 to 1, then facing that last guy 1on1 and murdering him, knowing hes already realized youve just taken out his entire squad is great.

Yep pretty funny having someone chase you and run them into a squad of blueberrys