I created a few sound fx and a background song a few weeks back, I'd saved them as mp3s. Ren'py recommends using the open format ogg for audio, which I agree is a good format to use. Using a free site http://media.io/ I converted my mp3s to ogg (if quality is super important then starting with wavs would be a better way to go), then all that was needed was the code in the game script, e.g.:
play music "act1-01.ogg"
play sound "fx1.ogg"
I also made some working backgrounds which I may end up changing, a Sleepy Agents intro image and some other image assets for in-game notifications (though much of this likely won't make it to the game).
|Sleepy Agents load up first draft|
I then coded in some bugs and got rid of them! This was trying to specify a new pixellate transition without reading the documentation!