Before you do anything the first order of business is to get your manuscript edited, not only for the simple spelling mistrakes ….mistakes. But also for grammar. This is the simple edit. Caution the spell checker in Word won’t high light things like spiel cheeker and they can make mistakes – I read a recent book (from a large Publishing House) where one of the characters was named Albi … spell checker had in places replaced it with Alibi….
After that comes the hard part – a real editor will read your manuscript find continuity errors – your hero was left handed but was writing with his right hand. He was short but had to stoop to go through a regular door type of thing. Editors will also suggest edits for readability and flow.
A word of advice do not submit your manuscript to either an agent of Publisher without at least doing a grammatical and spelling edit!