Starting new app. Where to start?

Hi there,

I have an idea for a new app and I have created an azure account for a SQL database and for creating RESTful services.

The database model is ready in my head but now that I want to start implementing several questions come to mind and I don't know where to start:

For best practices:

1- should I create the database first directly in the sql server (create database, create table, etc...) or should I create the classes in c# code first and then migrate them to the azure sql server?

2 - for creating a scalable app is it a good idea to create an Azure active directory and then create a Web Api in it to host my restful services?

3 - do you know any good resources for starting new apps guides