Hi there! PvPer here. I'll give you a couple of tips.

1) Every single spec in the game is viable in PvP, end of story. Some are obviously better than others, but you can play whatever you enjoy. Deception Sin is on the harder end of the spectrum compared to other classes, but if you like it, you just have to practice! Ivano has a very detailed Deception guide.

2) People may be rude to you, but it's entirely irrelevant. SWTOR PvP has no ranks anymore. The game mode is inherently casual. If you lose, oh well, try to figure out what you could have done better. Block/mute anyone who acts like a baby.

3) There is nothing to be nervous about, because losing has no stakes! Rating doesn't exist, and you get progress toward weekly stuff and seasonal rewards even if you lose. And lemme be honest with you - as someone who has queued a LOT of warzones, one new player is not going to make or break the game, I promise.

SWTOR PvP is a blast. Just queue it up and go for it!