In their simplest form, transitions gesture back at ideas you've already presented and then gestures forward to ideas you're about to present, providing a seamless, smooth, connection between the two.
In many cases, transitions might take the shape of a single word or phrase that provides links between paragraphs or sections in your essay. We will be looking at potential links between your sources today.
For instance, you might incorporate terms that imply addition (furthermore, in addition, additionally).
You might incorporate terms that imply sequential arrangement (next, first, second, third, finally).
You might incorporate terms that imply similarity (likewise, similarly, in the same way).
To show contrast (yet, however, conversely, on the one hand/on the other hand)
...to show cause-effect (therefore, consequently, as a result)
...to show elaboration (for example, for instance, in other words).
In each case, the word or phrase suggests a relationship between two elements: what you've already said and what you're about to say.
In each case, think about the about how you can signal the next idea, build on the previous idea, or reiterate the key terms as you advance your argument.