2. Read the novel aloud. The whole thing. You can find someone to read it to or just read it to yourself, but it really does need to be read out loud. I always find sentences I trip over by using this technique, which is a pretty sure sign that the phrasing in that bit could use some fine-tuning.
3. Similar to #1, but suitable for more "visual" people: create a storyboard. Does too much of the action take place in one location? Does the story jump around too much? How's the flow from one scene to another?
4. Make a list of all your characters' names. Most writers, if they've chosen character names they like, will unconsciously return to the same set of sounds (phoneme set? I never took linguistics, and don't know enough about the terminology to effectively look this up) over and over again. So you get novels that include characters named Jessica, Erica, Annika, Veronica, and Monica. Morgan, Aidan, Evan, Damien. If the names are too similar, it's hard for your readers to tell the characters apart. (Watch out for recurring first letters, too-- the "J" is especially common in my experience.) Time to do some renaming. On the plus side: if you decide to have a(nother) kid, you've got a starter list of possible baby names. So there you go.
5. Print out a hard copy and go through with a highlighter, marking all the dialogue tags. Are there too many? Not enough? How flowery do they get? If a writer uses dialogue tags like "exclaimed" too frequently, it tends to be a sign that they're not very confident that the emotion behind the character's statement is effectively communicated. If this sounds like you, and if you're right to be concerned, it's the dialogue itself that really needs work.