What was your biggest /facepalm moment?

4 of them:

My first character, imp agent. Didnt read my abilities at first and only learnt about out of combat heal at lvl 8

Imp agent again, couldnt get advanced class, assumed it was because I wasnt subbed so subbed as "I think I have to sub to get advanced class." still I managed to avoid the horrible f2p restrictions so facepalm turned good

Similar to OP I didnt see the "sniper" tab on the trainer until doing heroic with a sniper, he used cover pulse and I asked him what it was. He then explained the trainer has seperate tab for sniper (I was level 17 before I learnt this)

My Vanguard, got to level 31 and I decided a trooper would look good in KDY adaptive armour. Transferred credits across from other classes, as well as using planetary comms to buy suitable mods for all pieces. 140 planetary comms and 522k (brought weapons and dye too) later I was clicking reputation vendors and saw the "volatile shock trooper armour." Well im not changing my armour after having spent all that on it, just wished I had looked at all the sets before buying.

When EA fired all the staff and announced F2p.

Seeing stuff that has been datamined for 2 years yet still not showing up ingame....

That's OK. I post about how much I hate Kaliyo very chance I get

I'll only say one thing...

Not rolling a Jug Tank for PvP

I may have missed the fact that there were stats for the the first 28 levels........ Lv 28 mercenary rolling around with some willpower gloves, strength chest, cunning boots.... hey it looked nice, but now i understand why i would nearly die after every fight. note to self *bounty hunters use aim*

You eventually realized it, though . . . I've run into people at level 50 who hadn't yet.

There is couple....

Pressing "project" instead of "force lift" on SnV Oasis City (and yes, my abilities were on quickbar exactly on that order they appear there once you train them I also had never heard about keybinding or mouse turning )

When I realized you have unlimited range on TfB last fight I desperately ran after tank trying to heal him ... And naturally died to slam

Carrying ball to our goal with 5% HP on Huttball (Sage who pulled me off, thank you!)

Bashing Calphayus outside his shield and thinking why doesn't he take damage

Thinking "Kite Raptus" is synonymous for "Facetank Raptus"

And good old Corruptor Zero and his lasers ...

Yes... I am a noob and know it well

True story. At level 49 I struggled with my Shadow Consular to defeat the final boss on Corellia. I kept dying. My kin grouped and saved my hide. That said, later some random person on fleet whispers me my armor was all wrong and explained it all to me. It was half Willpower and half strength. My silly mind thought "Hey I have all these strike attacks, I need Strength!". Suffice it to say I think back fondly on this utter mistake lol. It was the most epic of my many fails. All the credits spent upgrading was wasted, and that being my first character it was costly.

I've also jumped that taxi railing on Coruscant which leads to a great sky diving experience.

Too many /e chat typos to mention. Forgetting to put the / can look so ridiculous.

I can't mention how many times I've pulled mobs during Heroic 4's just at the end. You know when the last enemy is almost dead, and you hit a number hotkey and Force Lightning or shoot at the mob next to the one you just killed because that last enemy died as you were pressing it? And this usually leads to your team being wiped because no one had a chance to heal and our energy is mostly spent so healers can't heal. Lots of angry teammates when everyone has to repair their high level armors.

I only just figured out how to turn this off (extremely annoying as my sniper, charging an ability and enemy dies, suddenly it chooses my next target for me and I have to try to cancel my shot before it fires, often failing).

ESC -> Preferances -> auto target next enemy (might be nearest enemy). its visible from the default page the prefences opens to.

This stops it happening, though also prevents you targeting enemys that attack you (when you speeder past and they shoot at you, you will now have to target manually.)