my tips are maybe different than everyone else's,
play on easy to start with,
play as the Allies on the smallest battles,
don't alter any settings until you draw then win on all of the smaller ones,
let the AI do the air part, and don't alter anything until you feel you have enough understanding on the air manual to do it better than the AI does it for you.
paratroopers, well it's a mixed bag, for me i tend to not drop them and use them as ground troops only, as if it goes wrong, the cost of loosing a high end unit like these can be high, so i don't take the risk, the gains can be great, but balanced with the costs if it goes wrong, i ferry / ship them almost all of the time.
until you fully understand how air power works, it's the best option imo, as once you master the air part, then you know how to fly CAP and interdiction and even marine patrols to make sure all your units arrive safely, well almost all,...