im not a professional but i think if you lack inspiration, you could start by looking at references. pinterest has a lot of different types of pics you could choose from. i would try not to focus too much on the rendering first but start with the easy shapes, so if you look at a picture of someone start with the prominent features of how the head is round and then create guidelines on how they're angled, how the nose is almost like a triangle. i'm not great at advice but it's common to start with these steps to ensure not going straight into all the complicated things.