The sew in I have now is self installed, short pixie done with 27 pieces hair.
It came out nice for my first time.
I was nervous because I'm good at doing other styles, but don't have a clue when it comes to any kind of weave.
Watching tons of YouTube videos helped.
I watched so many sew in videos it came to a point I felt confident doing it myself.
That very first track in the back took 10 minutes, had to get my swag with positioning the track and sewing. After that first track I had a good hand on it.
There's different ways to braid hair under the weave. Depending on the style, whether full weave or leave out, will set the foundation for how you will braid the hair under in order for it to lay flat.
IMO braiding the hair with braiding hair will help keep the style intact for an longer time.
And sewing in a net helps keep braids protected and organized under the weave.
Take your time, take deep breaths and you will do just fine.
It's a learning curb but lucky you have people to practice on