I used to hate wearing leggings because they would never stay in place! always slipping down because the elastic wouldn't hold up. It made me avoid them for a long period of time. But then I found a way to solve this problem.
Its funny because technically my mom and dad came up with the solution. When I was little, I was a off the walls all the time! And my skirts always used to fall down. So my dad brought different elastic string to put in my skirts. We tried them and eventually found the right elastic and viola, my skirts stayed in place.
I find that flat elastics don't hold up so well, and eventually begin to loose their elasticity. However, with ROUND elastics won't loose their elasticity for many many years. It will also keep your clothes up 10 x better. I never have to tug at my leggings anymore because they stay up so well. It really re-assuring and now I wear leggings more often. I made instructions using a pair of Cambodian leggings I just got that I want to wear to dinner tonight:
How to make your leggings stay up:
1) Get your materials: round elastic from a local craft store, scissors, safety pin, thread and needle, and of course leggings. (Its best if you use leggings made of a non-wrinkly material)
2) Find the back of your leggings
3) Locate the elastic and cut a little slit on the inside of the elastic part of the leggings. You can try to take out the already given elastic in the leggings or just leave it.
4) Take your round elastic and put a safety pin on the end of it
5) Take your safety pin with the attached round elastic and push it through the slit you cut earlier. Push the safety pin through all around until you reach the slit again. Make a removable knot on the end.
6) Wear your leggings backwards (tag in the front) and remove the knot you made, adjust how tight you want the elastic to be, and tie a triple or quadruple knot. You want to make sure the elastic isn't too tight nor too loose. If its too tight, it'll dig into your skin and leave a mark. If its too loose than it'll slip down. Now sew the slit that you made in the back close. Wear your slip proof leggings out, work them, and your done!