Firstly, congratulations, you finished your novel! That's a huge deal, so definitely treat yourself and let the world know. Even if you're going to hire an editor to edit/proofread your book, you should still try to do as much of it yourself as possible. Here are some tips to help you get through it!
Take a break
If you've only just finished your novel, I wouldn't suggest going straight into proofreading. This is because you need to essentially forget your story so that you can read it with fresher eyes, as if in the eyes of your reader. I would say that taking at least a week away from your book would be efficient enough. Don't take too long away from your story as you might forget to come back to it! Believe it or not, but this happens a lot. Authors will then go on to a new piece of work and essentially lose interest in the one that they've completed.
Proofread a physical copy of your book
This is my top tip for proofreading your work. You definitely need to proofread a physical copy of your book. When staring at words upon words on a computer screen, it can be really easy to miss mistakes in your novel but when proofreading a physical copy of your book it can be easier to focus on word for word of your book and it will give your eyes a rest from a screen.
Depending on how you want to publish, you should create an account with a self-publishing provider, like Amazon or Ingramspark, and then order an author copy. Know that, when publishing with Ingramspark, you have to create your title, upload your files and order an author copy so, unless you want to directly publish with them, you should probably use Amazon to order your author copy, as they don't charge.
Set yourself goals
First, before you start doing anything, you need to set yourself appropriate goals to help you manage your time otherwise you might miss any dates you've put out there, such as your release date or the date your work is due to your editor. First, decide how quickly you'd like to give yourself to proofread your work. This will all depend on how busy your life is, how quick of a reader you are and if there are any distractions around you. I am a very slow reader, so I like to set myself at least two or three months to proofread but you might find that a month, or even a few weeks, will work for you.
Then, decide how many pages you'd like to get through a day. To work this out, divide how many days in your deadline by the number of pages in your book. For example, if your book is 300 pages and you'd like to do it in one month, divide 300 by 31. That would be just under 10 pages a day.
Pro tip: Proofreading a physical book will help you spot more mistakes than reading your document online. Use sticky notes to section out your book to make the reading easier, and give yourself little milestone checkpoints.
Grammarly is a free, online tool that checks your work for any spelling, punctuation and grammar mistakes. When proofreading your work, it can be especially difficult to spot every single punctuation or spelling mistake. By using Grammarly, the site does it for you.
All you have to do is create a free Grammarly account and then copy and paste a chapter of your work into the site. You can then copy and paste the correct paragraph back into your word document which makes the changes easy to do. It is worth letting you know that Grammarly might not always be accurate, so if you need to feel free to ignore one or two of the suggestions, definitely make that call.
Take extra note of what dialogue words are used
Most of the time, you should use the word 'said' when accompanying speech from your characters. This is because using other words like alleged, declared, echoed can take your reader out of the story as it doesn't exactly roll off the tongue (or the mind).
Using these words every now and then is a great idea, as you don't want your book to be too boring, or sound super repetitive, but as a general rule of thumb, stick to the word said unless it makes sense to use something else. For example, if you want to portray that someone is saying something in a mocking way, it would make sense to use 'she mocked' at the end of the sentence to portray this.
Ask beta readers or critique partners to proof your work
The great thing about beta readers reading your work is that you can always ask them to pay extra attention to look out for any spelling or grammar mistakes. This is helpful because when working on your novel it's easy to miss things as you've probably been staring at words all month and you know where your story is going.
Find beta readers who are enthusiastic about reading books in your genre. Read this article on where to find beta readers.