The best ways to level up your Archwing are:
● Archwing Interception (Caelus, Uranus, vs Grineer)
● Arching Mobile Defense (Salacia, Neptune, vs Corpus)
An alternative option is to take a coordinated camping squad to:
● Survival (Ophelia, Uranus, vs Grineer)
Then camp near water, take turns diving in to switch to Archwing and get xp from your squad’s kills.