The first thing you need to do when you decide drawing step-by-step is to make sure that you have enough space to draw your subject on a piece of paper.
Then, use some shapes to sketch a first version of your drawing. This will help you manage the spaces around your subject more efficiently.
Also, you won't have to start all over again if the posture or the position of your character are inaccurate.
If you are drawing a human figure, then you might want to start with the head. If, along the way, you don't have enough space to continue, then at least you'll have drawn the essential part of your character!
It's also important, while drawing, to make sure that you keep the proportions of your subject accurate. If you don't do so, you might end up with a character having a big head or legs that are too long!
Don't use a marker or ink until you are 100% satisfied with your creation. You won't be able to go back if you are using ink too soon. That is unless your goal is to create a drawing with more spontaneity and fluidity.
Of course, some professional artists are able to draw nice cartoons without even sketching anything with a normal pencil.
Finally, don't overload your drawing with details, shadows or textures just to make it look more polished or less amateurish. The most efficient drawings are very often the most simple ones.
Just keep the lines that are essentials and add colors that will fit well together!