Outside of colleges and schools of journalism, few writers understand the power of transitions in making writing highly readable. In contrast, studies beginning in the 1960s illustrated the challenges that gaps between sentences posed to the reading brain. Gaps between sentences, researchers discovered, slow down the speed of reading and increase cortical activation—a sign that readers' brains are working hard to comprehend content, not a reflection of the sophistication of the content itself.
The antidote? That old standby beloved of teachers of journalism and of editors everywhere: the transition. Place words like also, too, furthermore, moreover, or in addition before the main verb in a sentence, and you signal to readers that the sentence they are beginning to read is continuous with the one they've already read. Or use in contrast, on the other hand, however, but, or conversely, and you help your reader understand content that hedges significantly on the content of the preceding sentence.
Transitions, crucially, provide valuable cues on how we should interpret content we're just beginning to read by flagging how it relates to the content we've just read. In addition, where you place transitions determines their effectiveness for your readers. Earlier is better, but, as long as you place transitions prior to the main verb, you're still helping readers to understand the sentence they're reading. However, place the transition after the verb, and you mitigate its utility. By the time your readers reach the verb in any sentence, they have already worked out the sentence's structure and meaning alike.
Use transitions and, as old journalism hands have long advised, use them frequently. The beauty of transitions is that you can never overuse them.