Visit this website for more information, but here is the basic help address for transitions: http://grammar.ccc.commnet.edu/grammar/transitions.htm
As we write, we take our reader on a journey that we are familiar with. As we write, we need to make sure that as we change directions in our writing, that the change is as logical to your reader as it s to us.
Remember, the transitional words will prevent the reader from going back in your writing and looking closely for a transition they might have missed. I may have missed a comma splice the first go round, but I won't miss it twice.