I Hope You WIll Find This Guide Helpful. I have 20 years in The Sign Stenciling Business, So This guide Is Designed  From Years Of Experiences Of Tried And True Methods.

 I first prepare my item to stencil on, clean your surface really good and lay your stencil down and align. I use small pieces of  painters masking tape to hold the stencil in place. I then prepare my paint in a styrofoam plate ( about a quarter size amount) . I use cosmetic wedges found in the cosmetic section of most stores. I seperate them in to individual wedges, I take the fat end of the wedge and lightly dip it into the puddle of  paint ( REMEMBER NOT TO MUCH )  and in a sponcing motion on a paper towel, remove any excess paint, giving it almost a dry brush effect. I then begin to sponce my wedge over the stencil covering any & every open area. Repeat this process  until the desired darkness. It may takes several times to get the look you are wanting, . Gently  remove the stencil, careful not to smear. You will notice there are tiny bridges in order to hold the centers inside of certain letters. I recommend  that those be filled in to give your item a completed look.  I use a #3 liner brush to do this with. I add paint to my brush and close the bridges with precision. making it look complete. 

   You May Want to practice this on a paper bag before you begin.