Always go for a good gun or equip yourself with two gun to gain advantage. I always go for sniper, rocket launcher and shotgun
Sniper and shotgun makes an effective combination
Another good combination is shield and pistol or revolver, shields can block you from bullets and bombs
Recheck your weapons and keep it loaded before engaging in battle
Try to maintain your rocket fuel full whenever possible.
If you get hit, try escaping and hide to regain your health
Wait for others to engage and then make your move by getting in the middle of the attack,
kill them both with a good gun!.;)this have always worked for me
Make good use of the grenades
Plant time bomb and gas bombs where your opponents will reappear, they will die instantly. All is fair in war.;)
Make good use of your weapons range, different weapons have different range.
Sniper have the longest range followed by rocket launcher and other.