Bending Tip - Relax Front of Tongue
There's a tendency for new benders to push their tongue hard on the face of the harmonica, using it as a type of anchor for the humping of their tongue. Tension in the front of the tongue, or the pushing of the tongue forwards onto the face of the harmonica, commonly causes thin and airy tone while bending.
The bending process starts behind the tip of the tongue for blow bends and all the way to the back of the tongue for low draw bends (such as the 1 draw). Focusing on relaxing the front of your tongue not only makes you a more efficient bender (only using the part of your tongue that matters), your tone and bending control will benefit.
Pick up a harmonica and tongue block your 3 draw. Focus on a relaxed, light touch with your tongue on the face of your harmonic (reminder, your lips and tongue are like a soft gasket, there should be no tension there). Start bending your 3 draw slowly, focusing on not tensing the front of your tongue nor pushing your tongue forwards to use it as an anchor for movement. Go all the way to the bottom of the bend and hold the bend, again focusing on keeping the front of your tongue relaxed.
Try this with all of your bends, you may find that you're relaxed on the bends you're strong on, and not on the ones that are challenging to you.