Examine both hands, with priority to the dominant. The dominant hand (right for right-handers) reveals your active life: choices, evolutions, present. The non-dominant shows innate potential and family heritage. Full reading compares the two to read the gap between potential and realization.
Why the dominant hand first
It's the one you use to act. Its lines record real choices, efforts made, paths taken.
If you want to read your life as it is today, start with the dominant hand.
Why look at the other
The non-dominant hand reveals what you were before making all your choices. It's the hand of temperament, not of lived life.
It says what life gave you, not what you made of it.
The comparison is where everything plays out
If both hands are nearly identical, you live in accordance with your starting nature.
If they differ much, you've transformed your life, through choice, trial, or circumstances.
A more marked dominant than the other indicates an active, intense life; the reverse, a more inner or constrained life.
Practical cases
For left-handers, the active hand is the left. For ambidextrous, take the one you sign with.
For a serious reading, photograph both hands flat, palms open, in natural light.