O.M.G.!! Lipgloss, Lipstick, Lip creams, Lip stains, Lip, Lip, Lip.... there are so many lip products that have invaded the makeup world, that we are always finding it difficult not to buy every single one!. I want to clarify that, you do NOT need every single one of them in every single color in your kit.
The 3 lip products you need in order to go from a super matte to a super glossy lip are: a clear lip gloss, a nude lipstick and chapstick. To create a matte lip look, you only need the lipstick in the color you want and some translucent powder. All you do, is apply the lipstick. Then, take a little bit of powder with a brush and dab it on top of the lipstick; and just like that you'll have your matte looking lip look.
For a super glossy look, you don't need the exact color lipgloss, you can always apply the lipstick and take a little bit of a clear lipgloss to apply on top. For nude lips it's the same, you don't need every range of nudes there are, you only need chapstick and your lip color is your nude color.
In case that you want to attenuate the color of your lips, because they naturally have a very strong color; your can use a nude lipstick, just add a little bit of it, and then apply some chapstick so your lips look moist and healthy.
The colors I always recommend MUAs to always have available in their kits are: Three shades of nudes, one more pink, one cool, and one brownish; two shades of reds, the classic red (Red Carpet Red) and a wine-ish red; and two pink shades, the classic barbie doll pink, and a hot pink. I also recommend that all of these are not a matte formula, try to choose a good quality of lip products so you don't have to apply thick layers since these can be uncomfortable for your clients.
I hope this was valuable information, and that you can now have a clear understanding on how to make every lip product of your kit more versatile.