When you see a long range tank in your team, don't ram it. I know it's tempting but he's probably scoping and concentrated. Don't annoy him.

Don't stick too close to them. If you just use them as a shield,
- You might not be able to shoot properly with a fat chunk of metal in front of you
- He might not be able to move freely and retreat if needed.

Stick around the light ones, they need you. But don't think you can take that much damage, just be a bait for a few seconds if they need to retreat.

Don't try to race with them. They're lighter and you trying to cut their path is a pain to the whole team, we need recons.

Don't go alone. You can try to lead the group, but if you see no one is following you, turn around and join the group. Otherwise you'll be most likely to stumble across a better organised enemy team that'll crush you before yours can join and help you.

When you see a perfect spot, a little elevated, with a nice bush to cover you, but a team mate has already taken it, you can :
-Try to fit in, if it's big enough, without being to close to your teammate.
-Push your mate off the ledge
-Take another spot.

Don't get in front of your team mates. They won't be able to make damages anymore.
The only moment when you can, is if you see one is in bad shape, and you have enough health to take damages a bit until he takes cover. Otherwise you'll be a pain in their butt.

You know thos little pre-registered, pre-translated messages ?
Don't spam.
Don't use them randomly.

Use it. That's it.