There are many ways to improve on the richness and the quality of your English. You will find here a series of tools to help you.
First of all, a large document which compares ways of saying things in different “levels” of language in order to differentiate when talking to a friend on the bus and when in an interview for a future job.
To revise your link words, take a look at this document : Link words
Remember that I have my lists of banned words ? good / bad / nice / interesting … Look at this document and work on improving the quality of your language Richness of language