What are the possible ways that I can use to promote my newly build mobile apps? Considering the methods of spending money also.
As you are willing to spend money. So, you will get many suggestions of using different kind of mobile app promotion services. I am not telling you that don't use them but I am suggesting that along with them try to get as much as organic traffic also.
Try using services like 'ComboApp'. They might take some money and effort at the first but they are totally worth it.
Try PPC. They may be not made solely for apps but they can bring plenty of targeted traffic.
You can use CPA networks in many cases they have worked pretty good.