Many people have a fear of the Crow or any arm balance. This is not such a bad thing. A bit of fear keeps us safe. Just don't become crippled by it. Ask yourself what you're afraid of. If it's falling on your face, put a blanket in front of you and don't do it on a coffee table! This pose requires more than just upper body strength. In fact, you'll find that you don't need a huge amount of arm strength but a lot more of core strength and physics (!) to help you.
THE CROW STEP-BY-STEP
Start in Malasana squat and bow forward deeply, placing your hands, shoulder-width apart and way in front of you, firmly on the floor. Your wrists should be in front of the elbows. Spread your fingers and press the finger pads and thumbs into the floor.
Hug your upper arms with your knees and keep the elbows bending back (not winging out).
Lift the pelvic floor and the lower belly, round the spine and lift your bottom up as you rock forward. Keep going forward until your elbows stack directly above the wrists. Look forward.
Make sure your foundation (hands) are firmly set with all finger pads pressing down, your core is engaged. Try rocking back and forth a few times to test out the balance. When you rock forward enough, your feet will float up. When they do float up, flex them and bring the big toes to touch, if you can. Keep your elbows hugging so as not to disperse your energy.
Keep breathing! If you think you're falling forward, drop your bottom down.