Long time ago, when Microsoft Azure platform was not yet mature enough, the best way to migrate SQL Server databases to Azure SQL Database was through the tool SQL Azure Migration Wizard , now known as SQL Database Migration Wizard.
The truth is that if we are working with SQL Server Management Studio 2012+ we have a task to provide us with this action simply by right click on the database > Tasks > Deploy Database to SQL Azure:
With this action, we can connect to our cloud server, choose the size and the name of the new database and launch the deployment:
Once completed will show a summary of each of the actions taken and the result:
Hope this helps,