Work with your teammates. They're there for a reason. Don't outrun them and get caught without support (or without striker boost!). If a guardian has a shield up, try to maneuver your opponent to fight inside the area where you're protected. But don't just stand idle on top of a guardian; if the same swing hits two players, the shield will break faster.

Actually, just never hold still. Move unpredictably and at random, but try to stay on top of capture points when possible. Your job is to maximize captures by your team, while distracting opponents and generally preventing them from capturing. Do not run past vulnerable CPs in your zeal to hit things: this is called Idiot Striker Syndrome (ISS), and it will cause your team to lose.

Don't attack alongside teammates by taking the exact same route at the same time, as this will allow a clever polaris user to hit your entire team with a single shot. Force opponents to spread their attention across multiple targets.

If you decide to play recon, don't turn on your cloak, then walk in exactly the same place as a visible teammate. This is very common, and very silly.