Beardies get most of their water from soaking, not drinking, so have a dish large enough to lay in, but only as deep as his/her leg joint. Do not ever mist directly on your beardie...if you do, and he goes under the light he can get severly burned(water acts like a magnafying glass). If you just got him, he may not eat for awhile...relocation stress can be shorter or longer...each reptile is an indivudal.
What size is your tank...what kind of lights are you using...and are you dusting your crickets? Dont feed crickets that are bigger than the space between his eyes.
P.S. No matter what you hear, sand is a horrible idea, google for pictures of Impaction and you'll get the idea. Slate tile looks good, easy to clean, and holds some heat in