Lightning Gun

This gun is super powerful in open areas.  Example; at Red Armor on DM6, I would primarily use the LG here when I’m down on the ground.  Would be almost pointless to use any other weapon unless a special situation came up.  The LG is so important in these fights that you make sure you deal as much damage as fast as possible.  If you’re not that accurate or you just can’t get a solid lock on your opponent that often, you should really work at this!  I spend hours on end training LG to make sure I’m dealing as high a percentage as I possibly can, always tweaking how I hold the mouse and my sensitivity.

Plasma Gun

Plasma is more powerful than most people think.  If you get a guy locked in a small confined tunnel or area, I would recommend Plasma over LG.  It rocks people more than you can imagine.

Rail Gun

I love and hate this gun.  It’s great to be annoying to your player, but I feel the Rail Gun really limits confrontation.  When I played PainkilleR, I loved that there was no Rail Gun because it made the game much more exciting with a ton more fights!  When the Rail Gun is in the mix, a person has a huge advantage to keep fights long distance and just snipe away.  If you feel this is your style, this is your gun.  But if you want to fight, you can always try to control the rail gun and don’t let your opponent have it at all and keep using your regular guns.  But, of course, by controlling this weapon, your opponent will hate you from long range.

Shotgun

Great weapon close range around doors and corners. Will do over 100 damage if you hit every shell.  This gun does a supreme amount of damage if you’re not careful, so if I know my opponent has a chance of having this gun, I’ll be super paranoid coming around a lot of corners and possibly even firing a rocket outside the door right around the edge to make sure he’s not camping there.

Machine Gun

Get good at this weapon like you’re good with the LG.  The MG could possibly finish off a kill that you just had with your opponent if he didn’t get any health.  I use to use this gun endlessly after a big fight I didn’t win, just to get the quick kill and get control back.

Pummel

Used much like the Shotgun for the first hit, but after that you just want to swarm your opponent as fast as possible and keep hitting him.  Hit him twice and you just did 100 damage.

Grenade Launcher

I love throwing these around and having them explode in important areas where my opponent might just walk right into it.  Don’t always think about throwing your grenade in a certain direction, think more about where it stops and explodes. That’ll help you a lot to do prediction grenades just like you try to shoot prediction rocket launchers blindly.

I hope this helped you understand the weapons a little more.  Ask some questions about any gun or situation you’re in during the game and I’ll respond in the comments.

-Fatal1ty