Owen records most of the songs in our packs (sample). These are the habits he swears by on a dawn walk.
Arrive twenty minutes before sunrise and stand still for a minute: birds go quiet when you arrive and start again when you stop. Keep the wind at your back so it does not blow across the microphone.
Record one bird at a time when you can, wait for a gap in the chorus, and keep your phone at chest height with the microphone pointing up.