first, ask him what he likes to read.
My brother has always hated fiction, he likes anything non fiction, so football annuals, minecraft annuals, Guinness book of records, Beano comic strip. If he likes fiction, things which are fast and exciting, ds loved famous five for a while, Beast Quest is good. Mr Gum.
Obviously you need a balance of levels, (above books are all quite easy for average 10 yo) what level is he? What can he read? Does he like reading at all, or are you fighting a negative attitude?
I would say that fluency is as important as comprehension, and that fluency then feeds into comprehension. So he needs books he likes that he can read successfully, and some that will push him on.
So, I would say that TV, computer etc all go off at a certain time. I think this matters because given a choice I have yet to find a boy who will volunteer to turn the computer off to read, but if the computer isn't on, they are more willing. Or, turn TV off at dinner time and make after dinner your reading corner, make it a mum and son time, curl up on sofa, keep it friendly and fun. Get him to read aloud for one chapter, chat about the story, ask him what he would do next etc If he finds it heavy going, then do alternate chapters, he reads one to you, then you read one to him. Hold the book so he can see it, get him to look as well as listen. Get him to ask you questions too.
You local library does a summer reading challenge, so you could go together, enroll in that, to give him some encouragement.