Okie... we're typing at the same time!
If your hair is fine you should start doing protein treatments, even weekly in the humid summer. It will help spring your curls and help against frizzies too. You should also look for a rinse-out rich in protein, and you can benefit from protein in your leave-in as well.
This is a popular and cheap protein treatment (provided you're not vegan or vegetarian) Pedaheh's Hair Blog: Science-y Hair Blog Recipes
. As far as purchasable PTs I really like Spiral Solutions Protein Repair Treatment.
Colorful Neutral Protein Filler from Sally's is also a great product to have on hand; you can add it to other products.