Whats the proper way to reject a contractor

[Steven J.]

I'm working through my first rehab and as I'm interviewing contractors and getting bids some of them just leave a weird feeling afterwards. Sometimes the guys just comes in WAY too low on their bid with WAY too much confidence in their abilities, other times its bad communication, sometimes I just found a better price out there.

What are some of the ways I can follow up with them letting them know I'm not going with them. Some of these guys seem nice enough and may do quality work - my main thing is I don't want to burn bridges because they may know my next contractor. 

I'd love the input! Thanks!