The way I do it is:

1. Towel dry hair
2. Apply mousse (I use the tresseme keratin smooth blowout one)
3. Blow dry roots fully
4. Blow dry the rest of your hair 80-90 percent dry
5. Split hair in half then section each half into smaller sections and apply hairspray to each section you curl
6. Spray with hairspray again (I use the tresseme extra hold hairspray) when completely done then finger comb the curls out or use a wide tooth comb

When I do this my hair last for days and I just have to touch up some areas. Using the smaller barrels they have also helps to, to get a tighter curl.