Most are easy when you have good directions to follow. There are many internet sites that have free tutorials on making bags and also videos on youtube.com . I found that the hardest part for me was finding the right interfacing and batting combinations. Everyone has their own ideas. You may want to take a class at a local fabric shop to get started. I started making tote bags to decide what materials worked best for me. I now have many patterns but the first bag's I made were from free patterns on the internet.
I use a light to medium iron in interfacing on the lining and regular high loft batting on the quilted outside. This works for me and my bags turn out light weight but hold their shape well but are still soft. Many prefer iron in batting. I have tried it but it was stiffer than I liked....just my personal preference. I have never had a problem quilting without adhesive. Some prefer to use a stiffer/heavier interfacing.
Hope this helps you take the plunge. It is a lot more fun to plan and make your own!
Lois