The best (and an added plus - the cheapest) product by far I have found to define curls is:
IC Fantasia Gel with Sparkelites (Clear or Pink) - I am so addicted to this product, it gives lots of shine to boot...
Do whatever you usually do for wash, just make sure you do a thorough detangle job (with conditioner), then rinse.
Pull your hair back or side as if your are going to put it into a ponytail (but don't band it) and then......Lightly wring (squeeze) your hair with your hands - no towel, no roughness.
Some good products to put in first are Infusium leave-in, then Scurl or Hollywood Beauty Carrot Creme, or you can skip these and go straight for the gel.
Then, thoroughly but gently apply the gel to your hair (you don't want to tangle it) - I mean saturate it with the stuff until you have coated every strand. Get all in the middle of your head too. I glob it on, then gently squeeze out any excess.
Next, gently comb through a little bit, but don't try to thoroughly detangle, just get the big ones out. I comb all my hair back, and flat down on the sides. I then take my Denman D-4 brush, and brush down the front and sides.
I finally give my whole head a spray with Revlon Finisheen and this gives it mega-watt shine.
Your curls will start to dry, and after a couple hours, if you want to, you can pull some of the curls apart for more definition.
The last time I followed this regime, I got superraves from the staff of a Curlyhead specialty salon when I took a friend there.
Good luck!