One of the best way to get vibrant watercolor -- Adirondack Dye Reinkers. Love these bottles! I suspect that you may get the same result with other dye reinkers, but I don't know as these are the only reinkers I have.
Unfortunately, Ranger has discontinued this line of products, but Ellen Hutson has them in supply as of the time I am writing this (linked below). I used the ones that are part of the Brights collection. There are also some available at Joann's and at Frantic Stamper -- probably other places as well.
The technique is easy, but result is awesome.
1. Take a piece of watercolor paper and lightly spritz with water.
2. Add a small dot of reinker -- this sample uses two colors, Watermelon and Sunrise Yellow. A small dot (don't squeeze the bottle!) is sufficient.
3. Spray with water and move the paper around until you are happy with the result. You can use a paint brush to help move the color, but if you want some white spaces, so let the color go pretty much at random and don't add too much water.
4. I did not tape down the paper (lazy). As a result, the center lifts up dramatically and that helps move the color. This will make a mess on your table, so do this on top of a water resistant mat and have paper towels handy.
5. Let dry naturally or move it along with a heat gun.
6. After it was completely dry, I took some gold Stickles and squeezed some on a mat. Using a piece of scrap cardstock as a palette knife, I applied the Stickles to the colored watercolor paper. The glue goes away and just the stickles are left. LET THE STICKLES DRY completely and you will be able to stamp over them. In this case, I stamped a sentiment from Ellen by Essentials by Julie Hello Gorgeous.
Gorgeous, or as the husband would say, gorgeousity!
MOOD WHEN DONE = Vibrant
Other supplies -- Clear and Simple Stamps heart Die, Memory Box card, Papertrey Ink White Linen paper, Ranger Archival Black ink.