Miss Sandra has it right. Carol Doak is the Queen of PP and is quite clear. Start with something simple. IMHO, Dresden Plate is about as easy as you can get. In my guild, even those who hated the idea of PPing were successful PPing plates for a fundraiser we did. The hardest part is getting used to thinking backwards.
1. When you position a piece, hold it up to a bright light to see if it is right. You might even pins and "open" it to see if it will fit.
2. Allow yourself plenty of fabric or precut your pieces.
3. Don't try it on a day that is already going badly.
4. It does seem like a lot of work, but the improved accuracy is worth it. (BTW, my first PPing project was a Mariner's compass for a friend who was dying. I got thru it in 2 days, but I strongly recommend against doing that.)