Depends on what type of app you want...
If you are an educator, which most of the people I encounter on a daily basis are, check out this Livebinder full of places to find the best educational app for your/your students' needs: http://livebinders.com/play/play_or_edit?id=36989. It might take you some time to go through the different areas of the binder, so start small.
If you are an app-enthusiast, and would rather use an app to find apps: try "appbzr". This app allows you to view several many different categories of apps: Entertainment, games, music, productivity, educational, social networking, sports, travel, books, finance, news, medical....just to name a few. The features on this app include: Top 100 Apps, Hot Apps, Price Drops, New Apps, Updates, and you can create your own lists to organize your interests.
If you prefer to read online reviews about apps: go to: http://appreview.com/ and http://www.appcraver.com/.
- Always read the reviews, especially if it is an app which has been around for a year or so. If the creator hasn't been updating to work out the 'bugs', probably not worth your money or time to use.
- Keep up with the updates. Don't disregard an app because it doe not function exactly as you wish at first. That is the beauty of apps--the updates!
- Create folders on your phone or iPad to organize your apps. You simply press down on the app until it 'wiggles', bring two apps together and it will form a 'folder' for you. You can drag any other apps you wish to your folders.
- Take a screenshot of the app you are using. (This is useful if your friend doesn't believe that you passed that angry bird level you've been working on.) Simultaneously press the on / off switch and the center home button at the same time. You will notice an on-screen flash. If you have sound enabled, you will hear a camera click.
- Have fun! Choose apps that are well worth your time and inspire you to learn!