Here's a quick little technique that you could use when playing with watercolor backgrounds from my Creative Market shop. Of course, there are lots of applications for watercolor, but maybe this method will give you some ideas and a new technique. The technique is pretty simple. Basically you use the shape of your text to mask out the watercolor texture. Bam. That's it. Once you've done it a couple times it should only take about a minute or less to do. I'm going to show this technique using some hand-drawn text, but as long as you can create a mask, the shape can be anything. 1. Add your scanned text on a separate layer in Photoshop.
2. Since I scanned my text, I tweaked the levels to blow out the whites and darken the black. This will help me to build a good selection.
3. Select > Color Range: click the white background to capture the area around your text and hit OK.
4. Selection > Inverse to create a selection based on the shape of the text.
5. Add a new layer folder, then add a layer mask to that folder using your new selection.
6. Add your watercolor into the folder. Either place your watercolor texture or copy and paste it. Since the folder has the mask applied to it, whatever you add to your folder will be automatically masked out. This means you can add multiple watercolor texture layers without having to worry about making new masks (plus folders keep you organized). Now is the time to play with the color. Make sure to tinker with the opacity drop downs and maybe even play with hue and saturation. I added a paper texture to the background and adjusted the watercolor texture's color.
Here's my end result.
There are other methods of adding texture to text, but this method allows a good amount of flexibility by utilizing folders. If you haven't seen the watercolor textures in the shop, go check them out!