As I notice my students often making the same English mistakes when writing papers, here is a list of some useful tips from the University of Purdue’s Online Writing Lab (OWL):
- How to connect different sentences with transitions?
- How to use articles (a, an, the, etc.)?
- How to use prepositions (at, in, on, etc.)?
- How to use punctuation?
- Active and passive verb tenses
- Making subjects and verbs agree
Another issue is not mixing US and UK English:
Some issues are also related to people’s mother tongue: