Products: Just like everyone else says: Chi Straight Guard. But I also find the Sunsilk Straight to Perfection works quite well and is a cheaper alternative to the Chi. Another product that I adore, but it is on the more expensive side would be the Bumble & Bumble Straight. It works like a charm!
As for the straightener: I have a Chi, but it is expensive but worth the investment, because if you are planning on buying cheaper ones, they will keep on breaking, therefore making you buy more, which results in you spending more.
I have keratin treatment in my hair. (The kind without formaldehyde. I know nothing is chemical free but this is apparently the lesser of the evils, and I love it because it is really a miracle worker. My hair is wavy at most and frizz free, and irons straight in minutes. Plus a blow dryer, just running it over my head until it dries, without using a brush or annoying styling stuff, will turn it straight.)
I also have an iron by the brand Fahrenheit. It is really good and stores like TJ Maxx and Marshalls sell cheaper hair irons by good companies. Babyliss and Croc are good too. I think my iron was only 30 bucks.
Before I had the keratin I used to use Biosilk but it made my hair oily. Keratin is my miracle worker.
I have used flat irons but they just fried my hair, what I did do to keep my hair straight was the Japanese straightening. It is a procedure that keeps your hair straight for many months; the stylist typically says 6 months but I feel it is more towards a year but it depends on your hair.
I just blow dry my hair after I shower, and then straighten it with a ceramic-plated straightener. It works wonders, and makes my hair really soft. If there's any frizz (usually there isn't), I'll just dab a really, really tiny bit of lotion and use it on my hair. Enough to get rid of the frizz, but not enough to make my hair sticky. But you shouldn't have too much frizz if you use a ceramic straightener.
moroccanoil shampoo and comditioner and their oil treatment then glimmer shine for the heat and some styling cream for moisture and their hair spray. It's really expensive but so worth it. Then I use a herstyle flat iron I got it from a booth in the mall and fell in love . My hair looks so healthy with the use of moroccaniol.
I haven't used chemicals on my hair in a long time! But when I did I used Rusk radical anti curler relaxer! It was a really good product that pretty much eliminated any curl in my hair. But I still used a flat iron.
As far as products- use anything rusk! I love their heat protection spray. Oh and that new John Frieda 3 day straight is really good!