Tip 1: Try to make things as even as you can. Use a ruler or draw lines on the paper to ensure that arms and legs are the same length.
2: However, you don't need to make sure that the proportions are perfect. The important thing is that it doesn't bother you. There's no need to make yourself crazy over the minute details like a slightly bigger toe.
3: Start with the eyes. They are the hardest thing to get right, and they help you place the rest of the features.
4: You don't need to go into perfect anatomical detail. Just draw enough so that you are satisfied.
5: Don't be afraid to experiment. If you don't like the mouth, keep trying until you get one you like. The face isn't set in stone during this stage, and it's best that you address any issues you have now rather than later when you can't change them.