1. If it's a unisex pattern, take that into account when buying it. I bought a large, and these are HUGE. Fine for the first time, but if I make the pattern again, I'll take in the seams by at least an inch and cut a good two inches off the top.
2. The pattern had side pockets and cargo pockets. I left them off of mine. That meant there were only two pattern pieces to deal with. Fast and easy!
3. Somewhere I missed making buttonholes or openings for the drawstring until it was too late. So I tried a few things, ended up with a rapidly fraying hole in the waist, and decided to try grommets. Not my favorite for this, but it fixed the problem. The ribbon tie is only for decoration because of this mistake. I really wanted a drawstring in addition to the elastic.
One thing about sewing...it helps to make notes on the instructions as you go. I always think I'll remember any changes I made, but I never do until it's too late. So this pattern is all marked up now!
Despite all of this, I think I'll probably make some more of these--you can never have too many pairs of pjs! I have some fun Christmas flannel sheets that would make cute jammies for winter.
(I've looked for a link to the pattern. I think it's out of print, but there are some on ebay if you're looking.)