Some people start with character while other start with plot.
But let's look at the seven elements all good writing should have.
1. Central idea - not to be confuse with theme
2. Character - talked about this one
3. Point of View - who's telling the story
4. Plot/ Conflict - the action in the story
5. Setting - where is the story taking place
6. Mood/ tone - the subject or general impression of the story - happy, sad, dark
7. Language - can be one of the hardest to incorporate into the story but extremely important.
There you have it the formula for a good book. Put them all in your writing and you'll have a winner.