1)Warm up:
for at least 5 minutes before you sing full strength – sing scales (search “5 Minute Vocal Warm Up” on YouTube) and/or use the “straw exercise” (search “Vocal Straw Exercise” on YouTube).
2)Breathe into your stomach/lower back, not your chest:
this helps avoid neck tension and throat constriction.
3)Visualize singing with resonance up and forward, away from the throat:
think of singing over the mic or imagine the sound is shooting out the top half of your face/head.
4)Practice a karaoke version of your song in advance:
to make sure you know the melody, lyrical rhythm (especially for rap!!), and required vocal range. Practice in a place where you can sing high notes with power (e.g., your car), since some notes you may find you can sing soft, but not with power. Record yourself to hear how you really sound.
5)Try singing apps for improving your pitch and ear:
“Sing Sharp” shows your pitch graphically versus where it’s supposed to be as you sing some of their library of songs.