Here are some of the most important lessons I picked up in my first year of sewing. This isn't an exhaustive list, but these are some of the things that I struggled with or that confused me at first. These tips and tricks should help a beginner who is just learning to sew.
Make your own high-waisted jeans / pants using this sewing pattern. It has a button fly. It comes in US 0 - 18 women's sizes. This post also has 48+ other sewing patterns for pants. A great source of inspiration for clothes sewing project ideas.