You will also want to signal to your reader whenever, for example, something important or disappointing comes up. In these cases, you will want to use expressions like it is important to note that, unfortunately, etc. You might also want to indicate time or place in your argument. If so, you will use transitions such as, then, later, earlier, in my previous paragraph, etc. Be careful not to overuse transition phrases.
Some writers think transition phrases can, all by themselves, direct a reader through an argument.
More often, though, the problem with coherence does not stem from a lack of transition phrases, but from the fact that the writer has not articulated, for himself, the connections between his ideas. Don't rely on transition phrases alone to bring sense to muddled prose. We have been talking about sentences and their beginnings. If the beginnings of your sentences must look over their shoulders at what came before, the ends of your sentences must forge ahead into new ground. It is the ends of your sentences, then, that must be courageous and emphatic.