Resistance Bands are a great way to gain the extra pull needed to deepen your favorite stretches. I also use ankle weights to assist in certain stretches. When you first use the bands you may find that they are not "doing" much, but once you find the correct elasticity to work with you will find that the extra tension is working your muscles without realizing it. Once you become more comfortable you can start to challenge yourself but make the band more taunt forcing you to really counter balance yourself.
Remember to take the time and stretch out both sides of the body. Many of us tend to favor one side, myself included. It is extremely important to keep our body even. Building the muscles up on one side of your body with cause unnecessary injuries. It is a lot easier to become uneven that it is to fix it.
Feels like I've got fingers dipped in just about everything, contortion, acrobatics, aerial silk, aerial hoop, static trapeze, and partner elements. ..But it is all connected through strength and flexibility. I believe that you should not have one without the other.