Since a tinted moisturizer is nothing more than a hydrating cream with some pigmentation, this is what I came up with and it's working fantastically for my.
What you need:
1. a empty jar (I used a empty loose powder eyeshadow container similar to this one)
2. foundation (I used my N°7 Stay Perfect Foundation)
3. Moisturizer/Hydrating Cream (I used Clinique Dramatically Different Moisturizing Gel)
4. serum (I used Dior Essential Skin Boosting Super Serum)
5. Mattifying/SPF cream (I used Dermalogica Oil Free Matte SPF 30)
Basically just mix together all the ingredient within the jar. Proportions between ingredients are really up to you: I did two pumps of foundation and one of moisturizer and mattifying cream each, 2 pumps of serum (it's a 5ml sample bottle though).
Foundation can be liquid or loose powder, it works pretty much the same. Just mix the powder really well or you'll get streaks of color on your face from unmixed pigment.
I would not suggest using a gel based moisturizer as I did, since it's a bit harder to mix with the other ingredients, but that's what I had and I made it work.
As I was saying, proportions depends on your preference/aim: if you want a moisturizer with very light coverage, use more more moisturizer than foundation (I'd say the ration is 2:1) or do the opposite if you want coverage with a little bit of more hydrating power.
I added the serum to have an extra hydrating factor on my skin and a bit of mattifying cream with SPF to add protection and control the shine on my t-zone. You can also use something brightening if you want, such as the MAC Strobe Cream.
What I got is a very hydrating, light tinted moisturizer that has light coverage but last quite a while on the skin.
With the proportion of ingredients mentioned above I get enough tinted moisturizer to last me about a week. I prefer having to mix the ingredients every week than doing a larger batch of tinted moisturizer because my storage solution (jar) is not perfect and I don't want to waste too much ingredient in case the moisturizer somewhat spoils.
It took me a few tries to get the result I wanted, so don't give up if your first try does not have the perfect shade or coverage! Start with a small amount of products to avoid wasting them if you don't like the results! the trick is to keep trying!