Getting businesses to advertise on your podcast, either at the beginning or end, or both, is a great way to create a revenue through podcasts. Most businesses won’t be keen to advertise on your podcast until you can prove a large number of listeners. Therefore, it is unlikely you will be able to start out from the get-go with sponsors. But once you accumulate regular listeners, or a high number of downloads from iTunes, you can start to sell advertising space on your podcasts.
However, like anything else truly worthwhile, apps require a significant investment of your time or money upfront. If you don't have the skills, then you have to hire someone who can assist you in creating a great app. But first you need to come up with an idea that will sell. Do the proper market research and analytics to come up with the right app.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.