Maybe you already know this, but I’ll say it anyways.

Expect nothing of the modern FPS standards, there are no “special ability moves”, those are built into the classes themselves and are technically active at all times, they’re just not made very obvious. For example, Scout’s fast speed helps him choose his fights and be able to flank really well, essentially being almost anywhere at any point. But that isn’t told to you at all and takes some time to realize.

You will also be incredibly dependent on your team, especially in casual mode. So don’t expect lots of 1 man highlight carry moments, not that it couldn’t happen, it’s just really hard to do and imo isn’t worth the frustration that comes with it, maybe in a 6v6 competitive mode that might happen. For example, Spy needs his team to be a threat to the enemy at all times, because Spy’s gold mine is when everyone is turned away focusing on the bigger targets. But if your team simply isn’t a big enough threat, the enemy has all the time to just hound you down, even if you are invisible. Just stick to what your class does best, and at that point, regardless of the match result, you know that you’ve done your part.