Having done most everything in the book, I may be able to help...
First off I am completely clean these days, and have been drug free for years. I don't personally encourage people to do drugs these days, as I know it's held me back some. But I know if someone is going to do it, they're going to do it regardless.
So with that here is my suggestion.
My personal experiences on acid have always been fun..... Usually hours of smiling and laughing and experiencing things in a new way was how it went down. However there have been a couple hours out of my hundred or so acid trips that weren't the best. Usually it takes something bad to happen, and then you just blow it wayyyyyy out of proportion then suddenly your having a bad trip. So you just have to remember that you on a fun acid ride and it will be over when it's over, then life will return to normal.... After a couple days ( =
With shrooms however... With me personally, I always have had bad trips for the second halfish of the trip. Usually my stomach began to hurt or something from the shrooms digesting improperly, and then my mind ran with it and bam, bad trip. On acid you may have some "dirty"/"achy" feeling but they were never bad enough to send my trip off in a bad direction.
I never did mescaline as a 15 or so hour trip has NEVER sounded fun to me.
My personal opinion if your going to try drugs, is to just do acid. It's overall a happier experience...
But honestly man, my true deep down opinion is to please not do hallucinogens at all. I highly recommend cleaning yourself up before you find yourself in jail, and then leading that lifestyle. I can assure you that a felony or any sort of criminal record will follow you for life one way or another. I just got my record expunged after many years... I had my fun, and while it was happening, it was a blast. Looking back I know I should've gotten my shit together earlier in life and life as a whole would be easier.
Go to college as it's the new high school... Make something of yourself other then another person that does drugs. The more you do drugs, then more drugs you will do. Before long you may find yourself doing some shit you never would've expected, and you may regret it later.
That my pennies