I don't work well with instructions, so already I'm sure you can guess the clothes I make will probably lack a little in the comfort department, but it's the love and time put into it, right?
First thing I would recommend if you're new to sewing, is practice making a couple pairs of PJ bottoms. Buy some inexpensive fabric so that you won't feel too awful if you mess something up. A PJ bottom pattern at JoAnns might be $5, look on the back and buy the needed yards of fabric, which will probably be 2 yards at about $3/yrd depending on what material you get.
I then watched youtube tutorials like crazy and most had great advise and tips, so definitely get comfortable watching the process here. There will be lots of trial and error, but once you're done making you're second pair you will probably be much better by the time you start your third with the nicer fabric. And try them on right away so it will give you some idea as to how small or big the pattern runs and you can adjust your chalk lines accordingly when you make all the other sizes you need.
Like I said, I don't pretend to have patience so the more detailed you are with prepping your chalk lines the better your garment will come out, moral of the story here, don't be like me. I'll admit, when making my Mom's robe there were some areas of the patterns I didn't understand, but instead of trying to learn the correct way to do it I just cut out all the pieces, pinned together and started sewing (a serger saved me alot of time for this project). My problem areas are always the underarms so I'm sure that fits weird on my Mom. Either way, she was wearing it a year later so it can't be that uncomfortable.
Would I do this again? Probably not.
Why? Because after spending my entire Thanksgiving 4-day weekend sewing 11 PJ bottoms and a robe, I went shopping at Old Navy and found $5 PJs in various sizes! I wanted to shoot myself.
Are you sure you wouldn't do it again? Well maybe, I like the idea of picking my own fabric and knowing that no one else has our look, so we'll see.