There are many types of resources that you can use in your writing. It is recommended that you consult dictionaries, both bilingual and monolingual. You may also use a subject-specific or professional dictionary. Some dictionaries and other resources are available online, either as an open resource or through the University Library.
Your word processor may mark out certain grammatical errors such as disagreement between subject and verb, for example "they is" instead of "they are". Nevertheless, it is recommended that you also use a grammar book or website.
Synonyms may be used to create variation in your writing. However, you should not attempt to find synonyms for subject-specific terms. Also be aware that there may be subtle differences between similar words, such as "write" and "record".