Question: I am currently working on an application in WPF/C# for personal use. I am not a "classically trained" programmer. Simply a hobbyist that likes to code in his spare time. Is there any accepted approach to the progression of application development? I. E.; Make it work, add fault tolerance, create a gui, then performance optimization. Or maybe should I design the entire GUI first? Basically I am going to start a new project soon and would like to have some sort of "every program needs this" checklist.

Answer: 
I'd say first of all, as simple as it sounds, write (either on paper or in your head) what the app is actually going to do. (Most businesses can't even do this part!)

Knowing that, sketch on paper what you think the screens will look like.
For example, say you're writing a home budget program and you want a drop down for accounts, and a grid for transactions, etc. Knowing what the GUI looks like will help tremendously.

Then fill in the details.
This is a huge topic that will probably garner a lot of opinions, so I'll chime in with this: Test-driven development. Try reading about it, and make the effort to incorporate it into your development strategy as soon as possible. TDD is the one thing I wish I had known when I started writing software years ago. It makes a world of difference in the quality of the stuff you put out.