Your curls are freaking adorable. It doesn't look frizzy at all in that pic. Just curly

If I may, I'd like to offer some contrary advice I wish someone had given me when my hair got to your length as I was growing it out -
Don't straighten it
Don't blow-dry it
Don't dye it or chemically alter it in any way
Don't rip through tangles with a brush or comb - I finger detangle exclusively now and do much less damage to my hair as a result
Do wash it as infrequently and gently as possible - start stretching out your washes and try to use more conditioner and less shampoo as you go, you may find one day you don't need shampoo at all.
Avoid things that have dimethicone and other *cones, these will leave a build-up and you'll have to use strong shampoos to wash it out.
Leave-ins shouldn't really be necessary - if it's dry, put just a drop or two of a light oil* on your palm and rub it in, so your palm is just a little shiny, then smooth that over your ends and length.
In a few years, when it's really getting long, you'll have the most gorgeous mane of curls and chicks everywhere will be super jealous of your hair, no lie. It's already beautiful, please don't ruin it with heat and chemicals!
<3
* - sweet almond, jojoba, or maybe coconut...find the one that works for you; my hair hates coconut, loves jojoba, and it's so-so on almond...there are other oils out there too if none of those work great...just don't over apply!