I'd say for a nice, enjoyable "buzz" try the 10x extract. If you want to really hallucinate, and have the chance at experiencing an either a) life changing thought or realization or b) the void, try 20x.

Read on erowid what THE VOID is on the Salvia page. Basically, it's the only other really reoccuring thing that many people see, and it's basically this black hole the size of a wall or a room that you start feeling you're getting sucked into, and that you can either go into this hole and die or that you'll be taken somewhere else. Usually, most people freak out and think it's going to suck them in and end their existence/take their soul.

Salvia can be very freaky stuff if you're not in the right mindstate.

The first time I did it, I effing did 40x without even realizing it. I thought it was only like 10 or 20x, but I think that saved my life. I kept seeing stuff that would freak me out, and felt like my entire right side had literally hundreds of thousands of pounds on it, like I was being crushed....but, then I kept saying to myself that it wasn't this powerful, that it couldn't be doing this. Things got really comfortable really quick. I ended up enjoying my "trip" so much, but the only problem was that I was sweating so profusely I went through two shirts (I was wearing an undershirt and my actual shirt), my underwear, my jeans, it looked like I had just went swimming.

I won't describe what I saw ,it'd make an already too long post even longer, but...anyway, yeah, I'd say try the 10x or 20x. Buy a little of both. =)