I have sites related to auto and jokes wallpapers, whenever I comment on a do follow site, I use real name like Mike tyson (sorry tyson uncle) my friend says I should be using names like wallpapers, Auto reviews which are relevant to site. What approach should I try, I think it would be spamming to use keywords as names in do follow comment system
Using Mike Tyson's name as an anchor text is pointless - are you trying to rank for his name? It's too competitive you won't do it by blog commenting. If you're not spamming, then don't put a link, if you are, at least do it effectively. Some blogs won't accept a comment with an anchor text link - but I think those same blogs will realise you're not the real Mike Tyson too.
I've read some blogs will add you to a spammers list if you use keywords - others do seem to accept them however. Check the other comments to see what the owner accepts.
You should need to use the name of your best keywords instead of real name so that you can get the keywords at Google ist page during searches.
The main difference you are going to get is that the link back will be optimised for the keyword, or not. You are still going to get value out of commenting, and getting a link back to your website, whether it is inline keyword or not. The best policy to commenting is, if you can add value to the discussion, then comment, don't panic too much about whether the keyword is there or not.