Paint will always do the same, this is known for many centuries.
There are so many ways to work with color, but the most important thing is that you understand color always does the same. I will try to explain it real short and clear so you can see the differences and yoiu know what they do when you use them, you don't need to stick with one method, you can mix them, just like your colors and do what suits you best at that moment.
Tint: Opaque (Titanium is most used for this) White + color. Making your paint lighter and opaque.
Tone: Opaque Gray + color. Making your paint less saturated and opaque
Shade: opaque (carbon a.o.) Black + color. Making your paint darker, less saturated and opaque
You can make gray by mixing white + black = cold gray. Start with white, otherwise you end up with a liter of gray, as black is stronger. This way you can mix several midtones, you can use a value checker tool to mix 7 or 8 gray values, black and white.
You can also mix complementary colors for a warmer gray, the colder your colors are that you mix, the colder the grey. This gray will be transparent. Cold colors are magenta till blue green. Warm colors are red till yellow green. Mixing a warm green and warm red gives you a warm "grey", as in brown. Mixing a cold blue green like phtahlo green and a cold red like magenta, will give you a more neutral gray.
You can also mix split complement colors for a warm gray. This will also be a transparent, unless you an add an opaque white, grey or black.
Mixing opaques: Start with your hue (target color), add the value (light/dark) with white or grey or black and change the saturation where needed. Too much of a color can be neutralized by adding the opposite color on the colorwheel. Too little color can be added with the missing hue, use the color wheel as your compass. The target color can go more to the left, (making the color colder if you hold the colorwheel with yellow downside) or to the right (warmer).
Transparents always get darker with every layer you add. Opaques stay the color that you mixed or bought.
Transp: fast results, as you can see your artwork as a lighter version of the final artwork, work from dark to light, save your highlights. Thin your paint to prevent overshooting.
You can erase easier, getting lighter with every layer you erase. It is a bit more grainy if you don't thin it enough or use too low pressure.
The colors tint very strong, as they are not weakened by an opaque.
They blend together, giving your color transitions, f.e. green is a transition between yellow and blue
They can be sprayed with a low pressure between 1.3-1.8 bar and providing an excellent airbrush control as they are so thin.
these are the main properties of transp.
Opaque is thick smooth, hard to erase in layers. It gets warmer and darker when you rub it soft and or completely white when you rub it hard.
It needs more pressure as it is thick, giving you less airbrush control and more tipdry. Use 2-3 bar to get it out properly.
You need to pre-mix your colors to get an accurate color pallet and then work from light to dark (lightest color first, you can give them numbers, letters etc, to mark them). The result is somewhat slower before you see what you do, as you need the contrast with the darker colors to see depth in your painting. You also need more paint for mixing, about 1 cm paint per color plus the paint you spill for testing. Testing can be done on the edge of a white paper. Spray 100% opaque, then measure and compare it with your reference. You can do this by isolating your color with a neutral color paper and a hole cut out. Usually a white paper suits best. Hold the testcolor on your reference and put the neutral paper with your cut out isolation window on both the testpaper and ref. Now see if you need to go darker, lighter, greyer, warmer or cooler. Add missing color.
You can also use a combination and then you better work on an opaque base with transparents on top, as opaques cover everything and give you a blueshift when going over a darker color.
Opaques can be thinned with water and used as a more transparent color, being easier to spray. It will keep it's properties of not changing value at a certain point, as the opaque has it's limit due to the addition of white, grey or black.
You can also check out the color2drop tool that prof Zsolt Kovacs made and put on his website, it gives you the recipe to mix colors in drops. It depends on the colors of your monitor, but if that is callibrated it can be really accurate and give you a head start, loosing less paint.
If you like to work transparent here is the basic to mix paint:
Yellow, red and blue are primary to mix paint, magenta, yellow and cyan blue + black are primary to mix in the print industry. These colors can make nearly all colors you need. Some exceptions for very bright and strong colors like violet can be a bit harder to mix, as blue and red just don't look the same. You could buy an additional violet. I use very warm primary colors, as it is easier to cool down a color then to warm it up. Cold colors are much stronger.
Mixing the primary colors gives you secondary colors: red + yellow= orange, blue + red = violet, blue + yellow = green
Mixing these gives you brownish colors. Opposite colors give you a neutral color, brown/gray
I hope this helps you a bit.