I have fine 3b hair. I donít straighten it anymore but when I did my routine looked something like this: I would wash it (at this point I was using normal shampoo and conditioner) than I would add leave in conditioner, let it dry a bit than I would take sections (2 inch sections) and would blow dry while straightening (I used a Bed Head 2 inch straightner or FHI Runway). The leave in conditioner I used was the large garnier fructis and sometimes I used some TREsseme heat protectant spray. I donít really remember having any problems with puffiness/frizziness except the times my straightner wasnít hot enough. I also found that the tourmaline straightners seemed to work better but I donít know if thatís because they can get hotter or because the brands that have them tend to be better.
Have you tried using just a leave in conditioner before straightening? In my experience I found that slathering a ton of conditioner on my hair (and letting it dry and get a bit Ďcrunchyí) worked much better than any other type of product. I havenít straightened my hair in a year but next time I do I plan on adding some coconut oil to my hair before (like maybe adding it with some conditioner after I wash and than straightening it the next morning). I would also maybe recomend looking at the plates on your straightener in my experience i found that some plates (worn or not smooth) can cause 'poofyness/body' cause they ruffle the hair.