What is your LFM/LFT pick-up line?

"Outrageously sexy [Level + AT] looking for a team!"

It works disturbingly well. The more titilating adjectives you add, the more effectively it works.

When looking for members, it's usually:

"We're doing x, would you care to join?"

When asking if a team has an opening, it's:

"Sorry to intrude, but would your team have use for a spare <x archetype>?"

My search comments are the usual "Please talk to me before inviting me, thanks!"

I used to put my powerset combos first in the search title, (i.e. archery/em blaster) but I found it's best not to do that on the 'power' team power sets. Anything empathy will never advertise as such, same on kinetics. Or Radiation emmision. My Mind/ permadom is quiet about it, as is my softcapped invulnerability/ tank. And so on.
...Basically power sets folks would invite to solve their problems. I just find that if they want me to be the one to come in and be the one to save the team in some way, it will mean less fun. (Often ending up trying to save a team from themselves.) If I'm another random member, and they expect the team to be self-sufficient, it's cool. If someone asks me my powersets on a character, I keep my distance right away. Once they invite me as just another player, I let them know what my specialties are.
Conversely though, I widely advertise my abilities if it's a character that won't do what people think it will- My Em/Dark brute is a mezzing brute, not a tank, so he warns people as such so he won't get roped into tank n' spankin'. My fire brute is crazy, and people will know to expect squish. My sonic/sonic corruptor will not heal or make people invulnerable, and is more about smoothing for a team than saving them. So I put that in there.

If it's a playstyle thing, I go that route: my kin/elec defender aggressively saps, so I let people know by calling him a 'sapper.' A similar warning goes for my 'ranged brute' crab soldier.