I'm alright with chargers, not great but okay. I think one of the best things for a charger is to hide your laser if you can. Some people hide the laser behind a ledge or wall and then peek out when their target is occupied to take the kill. (If someone doesn't notice you but sees the laser they'll start being sneaky and you may miss your chance) It's also worth mentioning that u should start paying attention to the reticle if u haven't been. I didn't at first, mostly focusing on the laser, but unless you are rather far away, killing is as simple as waiting for the reticle to become an X and releasing the trigger.
Also, if someone is already in a fight or just barely managed to defeat your teammate, they are likely injured already. If they are close enough you may be able to use a not-fully-charged shot to pick them off.
Also, this similar thread may help:
https://squidboards.com/threads/charger-tips.30445/
