most people have already in their pallette blue and yellow- just mix those
okay depending on the style, blah blah blah I D C to me it always looks out of place
this does go for most colours, not just green, but when introducing a new colour to a painting, using it straight from the tube stands out ! in a bad way ! from the rest of the colour pallette
making a nice green out of colours already on your pallette will harmonise the colours and make the overall colour scheme nicer to look at
whatever you need, a warm or cool green, having a selection of blue/yellows to choose from instead of pre-made greens will go a long way
add some red to your green too