Always work your rug on a flat surface, not in your lap. If you want to work on your rug in your lap, use a flat surface such as a lap board, portable ironing board, large book, or cutting board.
Increasing on the curves: On your first curve increase only twice, on the next curve increase three times, then you will increase three times on each curve for several rows. At some point you might have to increase four or five maybe even six. Watch for gaps and if there is a gap, increase.
If your rug is wavy, you are increasing too much. If you rug is cupping up, you are not increasing enough.
Your tension is set by your index finger; if you are right handed it is set by your left index finger, if you are left handed it is set by your right index finger. Don't pull you stitch tighter after you have taken you finger out of the stitch.
When you use a 2" wide strip, your stitch from top to bottom should measure 7/8".
When you use a 1" wide strip, your stitch from top to bottom should measure 1/2".
When you make your starting row it will twist don't panic ! After you make your starting row don't forget to make sure that your stitches are evenly spaced out on the runner. If they aren't spread them out a little and that will take away some of the twisting. Some of the twisting is ok.