What is a good transition sentence?

Non-Sequitur.

Is both a transition word?

And, in addition to, furthermore, moreover, besides, than, too, also, both-and, another, equally important, first, second, etc., again, further, last, finally, not only-but also, as well as, in the second place, next, likewise, similarly, in fact, as a result, consequently, in the same way, for example, for instance.

Is once a transition word?

after, afterward, always, as soon as, at last, at once, briefly, eventually, finally, immediately, in the meantime, in the past (or future), last, later, meanwhile, next, never, now, often, once, promptly, sometimes, soon.

What is a good transition sentence for a conclusion?

Transitional expressions

LOGICAL RELATIONSHIP	TRANSITIONAL EXPRESSION
Conclusion/Summary	finally, in a word, in brief, briefly, in conclusion, in the end, in the final analysis, on the whole, thus, to conclude, to summarize, in sum, to sum up, in summary