In most cases, a paragraph should have a single topic. If the connections between ideas are insufficiently clear, the paragraph may seem choppy or even incoherent. Relational phrases like therefore, because of, in order to, as a consequence of, the next issue is , etc. Good writing generally flows from OLD information to NEW information. If the order is reversed within sentences, the whole paragraph may seem choppy.
Old information is what the reader already knows and currently has in mind.
New information is what is brought into the discourse for the first time. I have a really old car. The fan-belt of my car broke when was on my way home. My friend was having a birthday party. Lights were on in a house by the side of the road.