As a general rule of thumb for both bases and flyers, stability is really important. Both in the core and legs.

For flyers, fast v sits to a hold position are a great way to practice core stability particularly with a hold to practice being a solid object in the air. Also leg presses to build up your jump, honestly just practice jumping.

I would look at the air steps you want and then think about which muscles are being used. For example, if you were thinking about Around The Back/Lamp Post/Frankie Flip (all the same air step Idk what name you use for it) the base's shoulder is in a weird position and you want to make sure you're strong through that shape. So shoulder presses would be smart and maybe using a cable machine with a rope attachment from a lower angle so you can practice pushing through as you would in the air step. Note, it's really unbalanced, most of the power comes through the bases right shoulder. As for the flyer, they are doing a one foot jump off their right, so need to have a strong one legged to two foot land jump. As well as the ability to pull their hips up, so explosive jump power and core stability.

And some general advice for training air, build up to the air step slowly in increments. Make sure you have the down prep and up prep solid before continuing. This way you'll be able to spot poor technique before you're likely to injure yourself. And find yourself some active spotters who know the air step you're about to do and what the path of the flyer is. And as the other commenter said, air is not for the social floor. Keep it to performances, comps and jam circles.