1. Spelling: are all words spelt correctly and used in the correct context? (Remember spellcheck will not pick up correctly spelled words used in the wrong context.)

2. Commas :

You should use commas to separate clauses (sections) of complex sentences. For example: “After talks broke down, relations between the two countries became even more strained.”
Words like ‘However,’ ‘Consequently,’ ‘Instead’ and ‘Therefore’ should have a comma after them if they are the first word in a sentence. For example: “However, there is evidence to contradict this approach.”
Before the words ‘and,’ ‘but’ and ‘because,’ you can either use a comma or leave it out, but if the sentence is a long and complex one it is best to use a comma to make it easier to read. For example: “The talks were conducted against a background of increasing distrust between representatives from both sides, and relations between the two countries deteriorated.”
Make sure you have used commas to separate items in a list. For example: “Relations between the two countries were characterised by distrust, hostility and caution.”

3. Full stops: are there any commas that should actually be full stops? Have you missed out any full stops? Remember: never stick together two grammatically complete sentences with a comma! Comma splices are one of the most common errors I see in essays!

4. Semi-colons: check that you have not used them excessively and that, where you have used them, you have done so correctly. Semi colons can be used to separate two complete sentences that are very closely connected. For example: “Talks were conducted against a background of increasing distrust; relations between the two countries consequently deteriorated.”

5. Paragraphs: are there any paragraphs that are too long or too short? Very short paragraphs can be a tell-tale sign that you have not developed an idea fully, but excessively long ones can be hard work for a reader, and might suggest you haven’t been succinct.

6. Apostrophes: Check that you have used an apostrophe combined with an 's' to show possession, but NOT to create plurals! For example: "The first participant's score was the highest" is correct usage; whereas "There were 20 participant's" is not!

7. Tenses: have you used the past and present tenses appropriately? Have you managed to switch between them effectively?

8. Missing words: check carefully for these, as it is easy to miss out words and not spot that they are missing, even after several reads!