I think using a 'professional' shampoo can make a big difference. I have always purchased shampoo's & conditioners from hair salons/suppliers.. and I can tell the difference when I use a supermarket shampoo/conditioner.

Like Renstar... I always put leave in conditioner in my hair. Whether it be cream, spray or serum.

Occassionally I use a hair masque - but normally when the ends are getting ratting and I'm due for a haircut.

Talking of haircuts - if you have split ends - its near impossible to get your hair really smoothe. So trimming off all the dead stuff can make a big difference.

And just blowdrying the hair can make a big difference. Pulling your hair tight (ideally on one of those round brushes)... and holding it to cool down before you release the brush. Once you've blowdried the hair, you can put some smoothing serum on the ends. Don't use too much serum though, as it can make your hair look greasy.

And don't try to emulate the models on TV and magazines... those girls do have beautiful hair - but they have professional hairdressers and their hair is then touched up to make it look perfect.