Before we write any actual code, it's a good idea to do some planning. Now, just because a tip calculator is a simple app, that doesn't mean what we make has to be of poor quality. If we're going to do something, we should do it right. So let's make the best tip calculator we can. One way I've found that's really great for brainstorming is to go on the Google Play Store and look at the user reviews of the most popular tip calculators. More specifically, I like looking at all the 1 star reviews, and writing down what all the best tip calculators are lacking. That way, I can better differentiate my own app, by making sure it doesn't have these same problems. So let's do that.

We can just search for tip calculator and look at the top ten results. Looking under the User Reviews tab for each app, we can click 1 star to filter out everything but the most negative reviews. Then we can skim through the reviews and pick out some of the things that are most complained about. See what I got, below.

Okay, great. Now we know what not to do, and by extension, what to do. Please note that I'm in no way saying these apps are bad. They aren't; they're the most popular for a reason. But they are imperfect, which is something we can attempt to take advantage of.