Just use a couple drops of a hair serum like ARTec Shine and Frizz Repair. Don't overload on serums though. You only need a few drops (about 3-5 drops) to get the full effect of shiny frizz-less hair. Too much will make hair look greasy.
Also when your straightening your hair try to first blow dry hair straight with a hair smoother like Redken Heat Glide. This will help lessen frizz, flyaways, and make it easier to straighten hair. Then flat iron sections of you hair with a spray on heat protectant like Matrix Iron Smoother. It helps to protect hair from heat and it helps to hold the style. Then use a hair serum to finish.
Another thing that can contribute to flyaways is using too high of a temperature setting. Most people with normal thickness hair should use between 170-180 degrees Celsius. If you have wavy, curly, or thick hair you can go up to 200 degrees Celsius. If you use a temperature setting that is too high for your hair texture it'll dry the hair out especially the ends making them look frizzy and dull/lackluster.