I have done my homework and have tried many Brazilian keratin hair straightener products. Here are my tips and recommendations:
First of all make SURE to use a formaldehyde free keratin treatment.
Secondly have somebody do it, its impossible and tiring to do it yourself. - Application is 60% of the whole result.
Try Sunliss? honestly its by far the best Ive tried... to a point that im not changing brands anymore... I normally buy it from their site www.sunliss.com and take it to my stylist. This way I save some $$$.