This was the number one question on the Curl Junkie Page on Facebook (if you haven't done so already, I invite you to "like" the CJ Page on Facebook) for the next topic to discuss on this blog. OK, so let's get started...
As with most things, there is not an easy answer for this since there are many variables. Things like the following will affect the answer for you personally:
1)Dew Points : I found a pretty good dew point calculator here, so you can find out what your dew points are at any given time and help you determine what products to use, but we will touch more on this later...
2)Hair texture, porosity, density - all of these will help you choose the best product to use for any given day.
3)Curl/Coil diameter/shape - in general, the tighter the curl/coil, the drier the hair tends to be so the more moisture/product you may need. That is to say, when the cuticle lies flatter (as in wavier, straight types of hair), there is less of a tendency for water to evaporate from within the shaft. When the hair bends more as with curlier types, then it is easier for any openings in the cuticle to let water escape (think of it like putting little pieces of tape on a slinky versus on a ruler. It is more likely that as the slinky moves the pieces of tape may raise up rather than when you move a ruler with the same pieces of tape.)...leading to more dryness.
4)Humidity levels where you will be spending most of your time - office space, the gym, outside in a wind storm, the steam room, etc. :-)
5)Damage to the hair - the more damaged your hair is then the more protein you will need in your products. The drier your hair is (in terms of feel), the more moisture/emollients you will need...
OK, so these are the more important things to consider in my opinion to start.
For me, what I have found is it all begins with the wash...be it a gentle shampoo or a conditioner wash (a method where conditioners are used as "shampoos") or co-wash. Try not to use anything that will rough up the hair shaft too much (some products people use as co-washes can do that I have found and lead the way to dry hair-usually because the product they are using was not meant to be used like this and are not specifically formulated to be used in that way). The next part is conditioning. I have found that if I am using good rich conditioners (as my hair tends to lean towards the dry side) on a daily (if not every other day) basis, my hair will stay moisturized throughout the day. My favorites from the Curl Junkie line are Curl Rehab & Beauticurls Daily Conditioner in normal-high dew points and Hibiscus & Banana Deep Fix & Curl Assurance Smoothing Conditioner for Normal-Low dew points. For where I live in the North East, this basically translates to Spring-Summer for normal-high dews and Fall-Winter for normal-low dew points (although this is not set in stone). Depending on where you live you could have higher dews most of the time (say in Florida or Texas) or more moderate dew points (say in California) or low dew points (like Arizona), so check out the dew point calculator to see how factors such as temperature and relative humidity relate to dew points. (This may seem a bit complicated for some but folks asked so I'm tellin'!)
Finally, you have to follow this with the right styling product and/or leave-in conditioner. For me, in the Fall/Winter time (low dews), my favorite styling products are things like the CoffeeCoco Curl Creme or Honey Butta. In the Spring/Summer, I prefer gels like Aloe Fix topped with a little Curls in a Bottle!, sometimes alone and other times over a little bit of leave-in like Beauticurls Leave-in Conditioner. In other words, in low dews I need more emollients (like butters and oils) in my styling products to help seal in moisture (and prevent frizz). The product can have humectants in them, just not a lot. In higher dews, I love a lot of humectants (like glycerin) along with something to seal in the moisture and add weight (which gel products do for me with or without crunch).
If I follow this routine with products I know work for me (like mine :-P), then my curls don't frizz out or feel dry and parched by the end of a day. If I want to try for second day hair (in other words, to refresh my dry hair when I get ready in the morning), I can usually use a spray like Curl Fuel in the higher dews and CoffeeCoco Lite in lower dews.
Again, this is what I have found in general and variations will occur. This is why you will have to experiment with my products and with other brands.
Lastly, I have also found that you do need to wash and condition your hair more often (every 1-3 days) for best results as far as moisture retention and the look of the hair. If you are doing styles like 2 strand twists/braids, then maybe you can go for a few days, but no more than a week is best in my opinion between wash/conditions.
I hope this helps and of course, if you have any questions, please feel free to post them! :-)