well as far as i know, there are two different things that can be used to thin the hair. Thinning shears, and a razor.
Thinning shears look like scissors with weird gaps in them. The technique to using these, it to snip about 2 inches from your roots, then snip about 2 inches away from your ends. (i use the word snip for lack of a better word...) you then comb through that section of hair, and you end up with a little hairball in your hand, and that section is now thinned. I have used this method and i do not care for it. My teacher did it for me the first few times, and then I did it myself (it really isn't hard) However, i ended up with the 2 inch pieces around my root (don't ask how
that happened because I don't know) and a lady straightened my hair once at the NY hair show and asked me if I had my hair thinned, and said "she could just tell" Needless to say I figured that wasn't really a good thing
With the razor, you just glide it through the section of hair, I guess. I don't remember thinning my hair with a razor, but people have done it to my hair for me. I like this technique better...you're not left with little pieceys, and you can remove so much bulk from your hair. After thinning my hair, there was enough hair on the floor to make a wig for somebody, and my hair was still thick! (no exaggeration)
As long as you go to a salon, you should be fine. they know what they're doing, whether they're using the shears or a razor. I don't think it would look stupid if you had layers (i have layers myself)...its just removing bulk from your hair. Some stylists have a problem with thinning clients' hair...they don't "believe" in it lol. Personally, I don't care, if you need your hair thinned then you need it thinned. But your stylist may not think its the best choice for you and may be able to recommend something else.
HTH