GAME TIPS FOR NEW AND SOLO PLAYERS
1 - Learn how the sights/scope work. Practice aiming using the green-dot scope or iron sights. This pays off big right away. Also remember that you are tagging the SENSOR DOME, not the player. This helps improve chances of scoring a tag at close range, and reduces frustration at long range when you can see the opponent but can't tag his sensor because it is hidden behind something.
2 - Learn the sounds of the game. Especially the out-of-ammo sound (which tells you that you need to reload) and the ejected sound (which means you've accidentally left the power core out and need to reinsert it).
3 - Choose the appropriate mode. The Shot Blast attachment works best for at-close-range shots and tagging multiple players at once. The Pistol mode is for longer ranges especially when the opponent doesn't know where you are shooting from.
4 - Use your shields. New players tend to forget this and take a lot more damage than they have to when an opponent finds them unexpectedly -- just raise shields and backtrack to a safe place, then you can control the engagement better by choosing how when and where to meet your opponent. Use your shield wisely, though since you do have a limited amount of shields each game.
5 - "Shoot and Scoot" -- if your opponent knows where you are, pop off a couple quick tags at him and then duck around a corner and scoot away -- he will probably first dive for cover and then try to chase you, at which time you can land a couple more unanswered tags as he comes around the corner after you. Do this a few times in a game and you are almost certain to win!