The most important movements to practise and perfect are jumping and landing. The standard PK roll is used to spread the impact of a jump over your whole body, and then flow into the next movement.
After perfecting the roll vaults would be he next basic movement to try. Vaults are used to clear or overcome most obstacles and there are many types. There are several vaults that are completely efficient and there are others which are used sometimes only to add fun to the vault, or make it look more impressive. These vaults sacrifice their efficiency and tend to be used less by experienced traceurs and more by freerunners. Most vaults are specifically designed to be used on specific obstacles. But learning specific vaults is not as recommended as learning to think on the spot and adapt easily.