1. Use a Splattershot (Regular or Tentatek, the Kensa Splattershot isn't very good, but you can still use the Kensa), it has decent Fire-rate and Damage.
2. Do NOT attempt to get a Super Clam early game, unless you got a straight route to the Goal
3. If a Teammate has a Super Clam, guide them. This meaning shooting in front of them to let them swim, and make sure you have some Clams yourself to throw into the Goal once the Super Clam is thrown (And if it hits)
4. Again, if YOU have the Super Clam, do NOT go back. If you go back and die, that just means you will have to cover more ground considering the enemy team may have already covered the area around it, and the closer you are to the goal after dying, the easier it'll be to score.

Take some of these with a grain of salt, as it may not match your playstyle. So just make sure to practice a few rounds with different weapons.