The one thing that can make or break your character is anatomy and silhouette. No matter how great your texturing or your lighting is, if you don’t get your form and proportions right your character will always look odd. You can add details later, so it doesn’t matter how long it takes. Study anatomy every day and even when you improve, work harder still and carry out your sculpting or modelling with the lowest subdivision possible that still enables you to get the main shapes. Detailing will come later.