HP Cobra recently stated that past life divination should only be done at advanced stages, since delusion and personal opinions/preferences can interfere in earlier and intermediate stages.
An earth sign is usually more hard-working and less adventurous, while an air sign is the opposite. Problem is, that is not necessarily the case for everyone. Heinrich Himmler was a Libra (air sign) but was a very hard-working man and was the head of the SS, which had a spiritual tendecy towards Saturn (earth) and the Sun (fire), not Uranus (air).
It's difficult to be accurate, but you can look for people who had the same tendencies and personality traits as you. My advise is not to limit yourself to signs and elements.