Well, I really can't help you when you're being outplayed Best advice is to take every game as an opportunity to learn the matchup and what you can do against different champions Practice in normals or look up guides and such maybe even go to the champion your facing against wiki and look at the cooldowns and use that to your advantage

When I'm team fights, prioritize a very important target, perhaphs it is their main damage dealer or maybe it's that soraka who probably has ult , or just anyone who you feel taking down will help your team win the fight (usually it's the adc) (Dont focus tanks or anything like that)

As talon your e makes you really slippery and you can quickly get in, assassinate, and get out and once you burst down the important squishy you should be able to quickly get out without dying

Sometimes when you're behind you won't be able to one shot the pretty far ahead adc , so maybe splitting might be a good idea

I'm not some high elo player or anything but there are plenty of guides out there that explain how to properly splitpush and when and how you should do it, talons splitpush is pretty decent

I'm not really a good player by any means but this is just what I've learned from my experience playing talon.

Heres some pretty useful yamikaze videos that should help you with combos and general matchups

Combo: https://youtu.be/1GIYLmDkQ4o

Tips against certain matchups: https://youtu.be/wDEwNfJ8eOs