I am not going to do a lot of recommending for the (paid) services of Writer’s Digest. They do a good job promoting themselves.
This one is interesting, since it provides an example of editor’s markup. It can be costly, but you may not have anyone handy to beg it off of, as a favor. Also, you may not have a friend who is really good at this sort of thing.
See also: Writers Digest (Helpful advice, some of it free, but be aware they are trying to sell you something. Lots, if you want it.)