The most commonly used basic transitional words are “conjunctions – and, or and not”. 
There are other such transition categories viz. Comparison, chronology, cause, examples, addition, clarification, qualification, conclusion or summary. 
Let us see words related to the given categories. 
Comparison: likewise, similarly, on the contrary 
Chronology: later, before, during, simultaneously 
Cause: because, since, therefore, as a result 
Illustration: truly, to demonstrate, specifically 
Addition: furthermore, also, moreover 
Clarification: in otherwords, put in another way 
Qualification: almost, possibly 
Summary / conclusion: given these points, in the long run