I personally have naturally wavy hair, but like to wear it straight more often then curly. I have highlighted/lowlighted my hair for years...and have always found that over the counter products have never done ANYTHING for me. I prefer Biolage as my top choice for shampoo/conditioner and I use the kind for color treated hair. I also use the conditioning balm twice per week. This has always worked for me, and Biolage is one of the cheeper salon shampoos. Just my opinion.
Also, I straight iron my hair as well, but I use a ceramic straightener...you can buy one of these at your local Sally beauty supply store. After I use that I put a product called "glass"by Paul Mitchell...and a pea sized amount goes a long way...it helps with the fly aways etc.