If you have Christmas Rifle or Enraged Rifle, equip it before the match begins. When the round starts, shoot while moving backwards to space out distance between you and the enemies. (Basically running away to a safer distance)
When you spot enemies at corners, switch to your ER Beamer and shoot in a "wavy" pattern while moving towards the enemy. The enemy will then see a barrage of bullets heading towards them.
When sent to the small arena, go for the left side or the right side ASAP. You don't want to get cross fired by enemies as it's really painful to take in. With guns that have small knock back, you can use them to help dodge lasers. Rapid fire guns like ER Beamer or Metallica Rifle can help ensure you hit the enemy while moving smoothly.
Avoid getting caught reloading when you intended to shoot. If you feel that you might reload soon, switch to a different weapon but don't switch back to your other weapon. Don't manually reload too often as it can waste ammo. During a duel with an enemy, reloading can really mess you up when it comes without notice. After shooting enough bullets, switch to a different gun when there a safe gap between lasers to avoid the reload surprise.