If you’re new to helicopter games in general then try using the AH-64D Apache together with the Radar Hellfire “R” to begin with. This will allow you to use the Longbow Radar to quickly find and eliminate the highest threats first.
The Radar Hellfires can hit targets up to 12km away and are totally fire ‘n’ forget so you don’t need to maintain lock for them to hit.
You also don’t have enough ammo to destroy everything so choose your route to evade enemy AAA/SAMs as much as possible.
To deal with long range SAMs you just need to break line of sight i.e. hide behind a hill. The missile is guided by the launching vehicle’s Radar so if the vehicle can’t see you then neither can the missile. Alternatively if you can destroy the launching vehicle 1st then that will have the same effect. Chaff will also spoof the missile but it may still hit you if you don’t move position.
If you’re feeling super clever then take some Sidearm missiles as these will home in on active Radar sources. They do take a bit of practice to use correctly..