There are quite a few tools that you can use to help you with your essay writing. It is sometimes a case of figuring out what is useful and why over the qualities of the tools themselves. Here are a few you may find useful.
This is a tool that checks your grammar and spelling, tells you what to correct, and gives you explanations why you should. It is good for students that have trouble with sentence structure.
This is a spelling and grammar checker that lets you get into detail about what type of essay you are writing and what level you are working at. It gives you specific suggestions that are relevant to the essay type and level.
A word and a phrase counter comes in very handy when you want to find out how often you repeat yourself. You may be using the same phrases and words over and over again in a very repetitive manner. You can identify this mistake by using these tools.
Your word processor will likely count all your words but not count words for certain sections. You can copy and paste those sections into the word counter to see how many you have written.
When you are working from a source, it is very easy to copy phrases verbatim and not realize you are doing it. Your professors are going to run plagiarism checks against your work so it is a good idea to do it first just in case you have accidentally plagiarized something.
There are quite a few of these on the Internet and they make referencing your work a lot easier. It also helps you to keep your references consistent, and that is the mark of a professional essay writer and will help you maintain a good grade through showing your care and diligence toward accuracy.