Once you`ve got some ideas and tip these kinds of questions will help you breath life into your creation.
1. Try to show other peoples your creations and ask them what they think. Ask them if they can pick up the personalities of your characters.
2. Don`t forget to aim your character to a specific audience.
Character design is often aimed at a specific kind of audience; it could be young children, teenager, girl etc. In case aiming your design for children try to create basic shapes and bright colors.
3. The importance of your characters eyes...
The size and position of your characters eyes tells something about your character. Bigger eyes gives a sense of childlike wonder, meanwhile smaller ones gives a sense of seriousness and depth. Wide-set eyes give a sense of oddity, while close-set eyes are often comic.