I recommend a "Specialized" Hotrock Girls bicycle. They are usually found at nice bicycle shops. Depending on her height you would want a 16" or 20". They are beautifully made and very LIGHTWEIGHT, which for a new rider makes things so much easier.
Please know that these are expensive! I'm sure most parents will disagree with my recommendation because the price is high, but we LOVE ours. My boys have had three Specialized bikes starting from the very beginning (a balance bike). Fortunately from me, both boys use the bikes, so I rationalize the price as only half.
We bought a Toys 'R Us $50 bike for my son at my sister's house and he hates it. It is so heavy and poorly made. But, a lot of kids that start out on these have no problem with them. My kids are on the small side, so a smaller, lightweight bicycle has been ideal. In fact, my oldest could ride a two-wheel, pedal bike (no training wheels) at age 3. My youngest at age 4.