I'm afraid if your hair isn't well cared for, anti-frizz serum will do very little for it. Try focusing on your hair care regimen, and use plenty of caring, moisturising products, making sure you take the time to use them PROPERLY. Shampoo carefully, making sure you don't over cleanse. Comb the conditioner through, and leave it in for a couple of minutes. This may sound stupid, but doing it regularly really does make a huge difference. Do a treatment or hair mask at least once a fortnight, and trim your hair regularly. For styling, invest in a blow dryer that uses ion technology: this helps alleviate static in your hair, which is a huge aspect of frizz.
If your hair is particularly porous, it might just be absorbing the frizz serum: try a leave in conditioner as well, and always rinse your hair with cold water. Remember, product isn't everything: you have to look after your hair to truly combat frizz.
That said, if all else fails, it may be best to put your hair up on really humid days!