I would def. suggest using mushrooms for a first time. My reasons being that it is a nice, strong, classic trip. I think for a first time it would be better than LSD because shrooms only last about 4 hours or so for me, starting out with an 8-12 hour trip on some 'cid can be intense, especially if you find that you do not like tripping as much as you thought you would. I also find shrooms easier to dose than acid generally. For a first time I would say you could split an eigth (1.75g) and still have a nice trip. Have fun, maybe find a sitter if you can for a first time!