It is not the safest way to start practicing maneuvers above the water, although much safer than above the ground. The safest way is practicing on the simulator. In paragliding we have pretty good simulator, a wind of certain strength and nice environment. There are a few advantages practicing like that: Instructor is able to stay close to you and observe and correct your mistake. You won't be shocked, because your legs are on the ground. Above all it is grate fun.