In the past and on occasions when I want to stay fresh I use a what I call a "Hybrid Palette" instead of a palette made up of hue value strings (aka. a "Closed Palette"). Normally I have each of the major Munsell hue families graded out in value steps 8/, 6/, 4/ and 2/. I pre-tube these and layout only what paints I need on any given day. Sometimes... I like to layout part of my palette in a more traditional way. Recently I needed to really overhaul this palette layout in preparation for a landscape painting class I'll be teaching that is based on using Munsell concepts. I revised this palette with and an eye towards being cost effective, versatile and intuitive. For the most part, paint brands don't matter except where cost is concerned. That said, since earth pigments can really vary from brand to brand, these paints are from particular companies so I don't have to adjust them to hit hue and value targets. This diagram shows how I layout the palette and the rough pre mixtures for each hue family using my newest paint list.
As you can see, unlike a purely traditional layout, I still have a neutral value string and a low chroma 5YR value string at chroma /4. This 5YR string is mixed specifically to facilitate flesh painting. On the top row I have each of the hue families represented as well as two intermediate steps at 10R and 10YR. I also have four low chroma piles. The low chroma 10R and 10YR are based on pigments that I use to mix my 5YR string with. They are left at their full chroma to help when you want to make a small bumps in chroma but without having to deal with a powerful high chroma pigment. The 5GY and 5BG low chroma piles are there to ease foliage and atmospheric perspective mixing. The 5GY pile is mixed using Chrome Oxide Green because I've found it's opaque nature and covering power really help when painting plant life. This pile and my 5Y pile do most of the heavy lifting when painting outdoors using this set up. Another thing I included is a Burnt Umber pile specifically for darkening my 5Y hue. Darkening with anything else shifts most 5Y pigments out of their hue family. For darkening my 10R - 10YR hue piles I use my 5YR 2/4 Red Umber based pile at the bottom of my flesh string. With the pigments I've chosen each one stays in it's hue family and looses less chroma using Red Umber to darken. All the other hues from 5GY looping back around to 5R can be darkened with black. I've found that if you darken the right pigments with black your head doesn't fall off and no one dies unlike what is currently rumored to happen.
I pre-tube all but a few of these hues because it is rare for a paint to hit an exact "5" in each hue family. It only takes two evenings to tube the whole palette since you are trying only to hit the correct hues. Some are close enough to work right out of the tube if you like. Viridian for instance is close to a perfect 5BG from most brands. The slowest going is tubing the 5YR string at chroma /4. This takes longer because of the careful mixing you need to do to achieve proper hue, value and chroma together. I chose the high chroma pigments for lightfastness and mixing characteristics. There are places where another paint choice, or even more paints, could have given me higher chroma but that was not my goal. I only wanted to have access to chromas I need in the majority of real world painting scenarios. For instance 5B and 5PB are cobalt based instead of, say, phthalo blue based. I chose these two pigments for opacity and drying rate not max chroma. All my low chroma paints also have a focus on drying time since these will be used for most situations.
I want to add this note- If you like you can use a green earth based pigment for your low chroma green. Most are chroma /4 out of the tube but most also tend to be closer to 5G. Natural Pigments offers a range of green earths that sit at roughly 10GY, 5G and 5BG. Choosing to do this is more of a matter of personal taste.
Incase you were wondering why I call it a "Hybrid Palette", it's because despite the partly traditional layout at the top of the palette the pigments are mixed to match Munsell Hue families and it uses Munsell neutral value steps to control chroma instead of using complements. If you are interested in using Munsell principles this is a good gateway palette layout. You will need the "New Munsell Student Color Set, 3rd Edition" or a similar Munsell product to use as a reference for matching hues and values (especially for the 5YR chroma /4 value string). Williamsburg recently produced a new "Munsell Neutrals" set at value steps 8/, 6/, 4/ and 2/.