Let's go talk about contrast. You know the basics: it's when two elements are different. Think big or small; high or low; day or night. But how do you apply this concept to lettering? It's more than just using black and white.
Obviously black and white is what everyone's mind goes to when thinking about contrast, but do you know why? It's a great example because it illustrates two polar opposites: dark black and light white. That is exactly what you're really going for with this design principle — two completely different things. You can achieve contrast through size, color, style of lettering, weight of lettering, weight within lettering (contrasting strokes), and so on. As long as you're creating a feeling of opposition, you're on the right track.
Contrast creates boundaries within a design. Remember that classic Helvetica style from roughly 2005-2010? There were no spaces between words and you could only figure out the breaks by one word being lightweight Helvetica and the next being a heavier weight Helvetica. LIKETHIS. (But better looking.) It's a perfect example of how you can use contrast to divide elements.
You can incorporate this principle into your lettering by choosing different styles for different words. Like bold type and thin type, or serif and sans-serif. This is especially useful if you're creating a composition with many words. You can use contrasting styles to guide the viewer's eye and tell them what words should be read together and in what order.
Another way to add contrast to your piece is by varying the thickness of the strokes within your letters. If you go this route, the general rule of thumb is to draw heavier lines on the down strokes and thinner lines on the up strokes. High-contrast strokes tend to give off a more elegant and sophisticated vibe, and low-contrast strokes lean towards a more casual look.
The piece I made for this post uses both methods for creating contrast. First, it juxtaposes both script and sans-serif styles of type. The script is organic and airy, and the sans-serif is structured and heavy. Second, I applied contrast within the strokes of the script. I wanted to keep a casual vibe, so there's only a slight variation in stroke weight.
These are just a couple of the easiest techniques for how to utilize contrast within your design. You could also combine textured text with smooth; vector with hand drawn; ornate with simple; the list goes on. Whatever your approach, using contrasting extremes is a surefire way to create visual interest by adding drama and excitement to your lettering.