I'd assume the OP knows better than to give his first timer friend three blotters after the experiences he's had on lower doses. What I've noticed with regard to psychedelics is that taking them together with friends in a sense makes the experience less intense. Having people to talk to and share what you are experiencing distracts you from getting completely lost in your own mind. First time I took acid was with two of my closest friends at the time. At times where I felt a bit anxious about what was happening to me, just telling them that was enough to completely take that feeling away. I'd say it's less likely you'll have a bad experience if there are others, especially ones you are close to, are around you. I'd advice for all of you to take the same dose as well as this creates more of a "togetherness" during the experience.
While it's impossible to completely control a trip, with experience (especially negative experiences) you can learn to steer the trip in a different direction. LSD and other psychedelics tend to have an impairing effect on short term memory. You can use this to your advantage, if you go about it correctly. For me, as soon as I recognize that I am having scary/paranoid/negative thoughts I try to distract myself by shifting my attention to something else (the sooner you do this, the easier it is). It can be as simple as looking at something else or getting up and walking around a bit. It can also be something a bit more drastic like changing the music, going to a different room or going outside. Because of the loss of short term memory it's quite easy to become completely engrossed in something else. Going outside whilst tripping tends to be more fun with friends, preferably going to a nice park at night (so there's less/no sober people to worry about). Walking around and talking about whatever can be a great way to really explore your trip.
If that is not enough to take your mind of things you can also try switching the emotional content of your thoughts to very neutral things. When in a negative mindspace, thinking positive doesn't really work, your tripping mind will instantly convert happy thoughts into bad thoughts. Neutral thoughts bring out neutral emotions. A simple way of achieving this is by describing the things around you to yourself (as in: "that's the table, it's got four legs, oh look there's stars dancing on it's surface, the stars are green and dance around in circular motions, there's my poster of the beatles and there's my friend staring at his hands, he must be having a good time. There's the door and if I open it I can go to the kitchen, etc."). You'll find that this can effectively calm you down quite quickly. Once you feel confident again you can start having fun again!
Alternatively, you can take the harder route and delve into the negative thoughts full on. Investigating them for what they are and questioning why you'd think that/feel that way about whatever it is. This can evenutally bring you to some pretty bad places, but acid doesn't last forever and the effects will wear off. Once you do come out of the trip you'll be glad you went through it. I find it harder to do this if there are other people around as they'll distract your train of thought.
In case on of your friends starts freaking out, it's important to take care of them as soon as possible. Ask them what's going on, if they'd like the music on/off/changed, some water or food, etc. Just showing that you are there for them and everything is ok is usually enough to pull them out of the bad space again.
Eventualy, the best way to go about it is to convince yourself you'll all have a wonderful time and no one is going to have a bad trip. If you are not afraid of the bad trip it will never happen!
Have fun dude!
