This guide. In geoscape strategy is said setting up second base on first month is risky, so I waited to second month. What comes to # of hangars & aircraft, even with 5 interceptors I could not bring down every UFO that appears on radar: they're either damaged or refueling, and corvettes need at least 2 aircraft to bring down even with alienium ordnance. I take 1 F-17 only against small scout, all other UFO I use at least 2 of them. And there can be 3 UFOs going around Eurasia & Africa at a time.
Real military doesn't use shields, so why should I? My squad composition is 4 riflemen, 2 assault (shotguns, stun batons), machine gun, and sniper. I chose shotguns because of modifier for reaction fire, and those are really useful indoors and storming UFOs. Sniper has reach (if he can get LOS) and I use machine gun to cover the flank (and UFO's door) as rest of the squad explores the map. I don't use grenades in every deployment: frags destroy salvage and gas grenade is useless against androids.