As I go through my writing journey I have learned several things. Things that I will need throughout my writing career.
One: Do your best to write in the correct tense in the beginning. That way it is something that does not need to be edited when you come to that process. It is already done. Of course, there will be times when you forget, but that's caught in the editing process.
Two: After you finish your novel you are NOT done. Not by a long shot.
Three: Do an edit for structural errors. Do you have commas where a period should be an vice verse. Are you using a colon instead of semi-colon. All of this is important. If there are too many errors the publisher will dismiss it. They want a polished manuscript, or one with very little errors in it.
Four: Find a beta reader. This person will be someone who reads and/or writes in the same genre as you do.
Five: While your manuscript is at the beta reader you will do another edit. This time, you will read your story out loud as you edit. Does it sound right? Does it read smoothly or are there bumps along the way? As you read out loud you will make more changes.
Six: Listen to what your beta reader says. You may not agree with everything they have to say and you may not make all of the changes they suggest, but you have asked them for their advice so please listen to what they have to say.
Seven: After all of your edits, including the one from the beta reader, get another beta reader. They may catch something or have a different point of view than the first one. And again listen to what they have to say.