For that I just remember
the letters 'ERTM' in order.
They refer to the order that the graph lines appear i.e. EAS, RAS/CAS, TAS, MACH.
When the question tells you which one is constant, that is a straight line up
the page, anything to the left leans left and anything to the right leans
right.
eg lets take constant CAS:
CAS straight up the page. EAS is to the left of CAS and so leans left. TAS and
MACH lean right.
If you are climbing, start at the bottom by the X axis and see which way the
line goes. If it’s off to the right, its increasing
& if it’s to the left its decreasing.
Descending you start at the top and do the same.
All you need to remember is ERTM for all cases