sPVP Questions

I think partially it is also the fact it just feels bad to lose or feel like the skill gap is too vast (this just takes time to acclimatize to measure yourself again your own best worst performances and only use others as inspiration rather than a measuring stick) i think honestly not being able to deal with the fact that if spend time in pvp you will find match up you destroy and opponents who destroy you and everything in between those extremes.
I will definitely look to spend some time in the private arena when i see people are playing or looking for people to play in it.
I could also use some practice as presently i find good eles, mesmers and thieves near impossible to deal with unless they mess (playing mostly on a dps guardian and a warrior). Eles i find tough because it feels they can sustain forever while also pushing out healing and damage in the same build pretty effectively, mesmers are tough because between clones/dodges/invis/invuln and cc if they don't want me to do something i don't feel like i have a solution, thieves just tend to stealth and shortbow 5 away from any fight they feel they might be losing and blow me up out of stealth. Any advice people have who either play these classes or find them to not all that hard to beat would be welcomed. Thank you.
Condi engi is also painful since i feel like i melt if they look at me but i haven't faced many so maybe i just need time to figure out what abilities i need to be looking to mitigate and which i can't get hit by without immediately keeling over dead.