First of all, no matter what hair straightener or heated hair appliances you use, you should always use heat protection, especially if you are doing it more than just once a month. There's heat-protectant products that are out there, but the one I recommend above all is the Aquage Beyond Shine Heat Protectant Spray (easily available on Amazon). You just spray it onto sections of your hair (should be dry hair) and comb it through. A little goes a long way. You can also pair this up with other Aquage products like the straightening gel but another great line of products is from Aveda. If you've already damaged your hair, the Smooth Infusion Naturally Straight is pretty awesome. Aside from that, I would advise for ceramic tourmaline ionic hair-straighteners like GHD, Chi or Coroliss. Also, when it comes to matters of the hair, it's better to check on reviews and if you intend to use it regularly, get a higher-end professional model because it makes all the difference in professional results without the damage that lower-end products would cause. Now if you want straight hair on a weekly or daily basis, then I would recommend you consider Keratine Treatments at a reputable salon.