Revell snap (Skill Level 1) kits contain "Peel 'n Stick" type self-adhesive decals that are applied by simply peeling the image from the paper backing and applying to the model. Skill Level 1 kits are found under various names including Easy Kit, Thunder Squadron, Wheels of Fire and Snaptite. Kits that require glue (Skill Levels 2 & 3) have traditional waterslide decals.
Here's how to apply these:

1. Cut apart the individual images from the sheet.
2. Dip the decal into lukewarm water for 1 or 2 minutes. Take the decal from the water and see if the image will move or slide on the paper backing. If not, return to the water for a few more seconds.
3. Once the decal will slide on the backing, put the decal and backing on a paper towel for a few seconds to remove the excess water.
4. Then bring the decal up to where on the model you want to apply it and slide the image from the paper backing onto the model. While wet, you can still move the image on the model a bit to position it just where you want it. If there are any air bubbles under the decal, gently push the bubble toward one of the edges of the decal with a wet Q-tip or edge of a paper towel to remove it.
5. When the decal is in position, simply leave it air dry and it will stay in place.

Many hobby shops will sell various decal setting solutions that will help the decal conform to sharply curved surfaces. We suggest trying out the specific solution you wish to use on an unused decal from the same sheet applied to a piece of scrap plastic to make sure the solution will not react with the decal. If you wish to spray a clear coat over your decals, the clear paint you intend on using should be tested first using the same method. Unused waterslide decals may deteriorate over time due to storage conditions such as heat, moisture or exposure to light. If you have an older kit, you may wish to test one of the decals on the sheet in water to see what kind of condition they're in. Use one of the markings you were not planning on applying to the model or use the small kit number or copyright info markings usually found on the edge of the sheet. If they break up when placed in water, they're getting pretty old. One way around this is to brush on a clear decal film. This is a liquid product made by several companies including Badger, Microscale and others and found in many hobby retailers and online. One last trick-exposing an older decal sheet that's starting to turn yellow to bright sunlight for an hour or so will usually clear that yellowing right up.