Relatively new mesmer here, (300k exp), have a fair few skills now, although still lacking on some elites as i plod through factions < not gotten to tyria yet

Now, there are numerous threads about which skills to bring, what are good builds etc for PvE.... except they mean nothing, this is far and away the most involved class i have played and love it to bits, but, skill selection is majorly dependant on knowing what is in the mission it seems to me, do i go interrupt and try to interrupt key skills on multiple caster targets, do i go warrior hate, do i go ilusion and degen spam things, do i go one target total lockdown, do i go for dmg and let the enemy cast/attack as they will.
It's a dilemma i face every time i go into a mission, i have to know what skills to bother interrupting, which to leave, do i take backfire, what are other people going to be doing, and truth to tell im finding it difficult. I take shatter hex into a mission because i know there are mesmers/necro's only to find they dont do much in the way of hexing

So i guess what im trying to ask is, what skills do you guys consider essential, which situational, and which totally naff? Are there some skills u simply dont enter PvE without?
I am mostly focussing on domination atm, although after reading a few more posts this evening im going to try illusion.
As a staple, i have been taking Empathy, Backfire, Power Spike, Leech Signet, Energy Tap, FC Res spell, then kinda messing with different ones for the rest of the slots.
Sometimes it just doesnt cut the mustard though and i don't know why, i know i have done my job, i have preventeed a whack load of dmg from those le bosses and mobs, and helped keep my group alive, but i just dont feel optimal.
Any tips on how you play yours? How you prepare before battle? Is there a "standard build" you take into a new mission where you arent sure what you are facing? Then optimise it next time you go there?
This forum is full of great tips already, and believe me i have spent hours reading it, but this seems to be the one class where reading a forum, whacking it onto your hotbar and plinking away doesnt work.
But i love it

-Kiyoko Oshiro
20 Me/x