Jim: If Oso's link has already covered this, apologies for the repetition. I've got two small points to add to the very good advice already given above. Myself, I rarely hand grab or catch - unless it's the best option in a tricky situation. We use a
P4P, not a P3a, so I'm assuming/hoping they are basically the same when it comes to catching them.
First, be careful. The props can cause bad injury. Search YouTube for Enrique Iglesias trying to catch a drone during one of his concerts. Someone in the audience filmed what happened on their phone. It's a good example to be cautious (but not frightened).
My second point is to warn you that once you've initially got hold of the drone by the legs or a landing skid, be aware that the drone will want to pull away from you - a bit like a scared or angry captured animal wanting to escape - making an extra loud noise. Don't panic when this happens, instead focusing attention on shutting down the motors.
As an extra thought, we never take off or land on grass. We use an old tarpaulin - or, occasionally, a piece of board - laid onto the ground. And we do our best to find a flat, or nearly flat, piece of ground. This reduces the chances of tipping over to nil, unless there are very high winds. It also minimises any risk of damage to the camera lens etc.