2 drops should be more than enough if it's your first time. Depending on the potency, 2 hits may even be too much. I used to get incredible acid and I'd fry hard on 2 hits, even had a couple of really intense ego trips on 2 hits.

There's a lot of shitty acid compared to good, though - it's all the same, some is just more cut than it should be. The average dose is probably around 60-80mics... a good strong dose would be closer to 100-120. Liquid is typically on the weaker side, depending on who you or your dude's dude is getting it from. It'll only get cut once it's in a single vial, most of the time.

I'd say...buy 2 hits, put one on a sweet tart and take the other one. Wait until you come up and see how hard it hits you, if you think you want more, than take the other hit.

As for the setting, it's the most important part. You have to be in a relaxed spot with nothing that you'll have to worry about. Make sure you are with people you TRUST. Trust is a big deal. LSD has a way of making a person realize his faults and the faults of friends. I went through a big re-adjustment after a pretty hard trip where I withdrew myself from the group with which I was chilling. Realized that a lot of my 'friends' were shitheads, and that I basically accepted them because of the drugs or company with which they surrounded themselves. It will definitely show you a lot of pseudo-relations, and if you're uncomfortable with really getting indepth with these kind of thoughts, make sure you are around people that you love.