Most people just use oil I think. I really like jojoba and grapeseed oil since they are light. I use either by mixing it with my leave in conditioner and smoothing it over the body of my wet hair. So maybe take a dime-quarter size of your TN conditioner while you're still in the shower and add a few drops of oil. Or just smooth the oil in your palm and glaze your hair with it once you're out of the shower and not dripping, before you apply your curl keeper. But you're right if I'm using the SM milk or the smoothie as a leave in I tend to bypass the oil because those products are so moisturizing I believe they seal me all on their own. And yes you can also use straight up AVG to seal. It's really good at regulating the PH of your hair which makes your hair far less prone to frizz. I haven't tried it yet but I throw it in my FSG and that stuff eats frizz. Just like KCCC. Also user rmc2 I think told me she mixes Lily of the Valley aloe gel, 3 parts that to one part jojoba and makes a hair gel out of that. That sounds like it would keep any and all frizz out if you were just to make a mixture to seal. Maybe treat it like a leave in conditioner before the curl keeper/finishing product or something. . .
3A - C, HP, ME, HD. (Coarse, High Porosity, Medium Elasticity, High Density.)

CG since Nov. 2012

Poos: SM Moisture Retention + Yucca Baobab, TJ's Tea Tree Tingle
Condish: TJ 'sTea Tree Tingle*, SM Moisture Retention* + Curl & Shine + Yucca Baobab, Yes to Blueberries
Stylers: KCKT*, SM Curl Enhancing Smoothie* + Curl & Style Milk*, KCCC*, FSG*, CJ Pattern Pusha, Curl Keeper
Sealers: Jojoba* or Grapeseed* oil

* = HG