Hi! I've been recording myself sing, and I've noticed that I sound sharp or flat on some notes. Do you have any tips to fix this?

Hi, Tiffani! The solution will depend on why you're going sharp or flat. Some things to consider are:

1. Are you breathing right before the phrase in question, so you're properly supported?

2. Are you in the correct register for your range? 

3. Is the vowel causing issues? (Try a different vowel shape and see if it's easier, then modify toward that vowel)

4. Is there a tricky leap leading up to that pitch? (If so, isolate that leap and practice singing it in tune)

Most intonation issues have to do with your ear: get into the habit of singing the correct pitches in your head before you sing aloud. We call that "audiating", and it's immensely helpful in preparing for a pitch and executing it well. 

This tutorial has more tips on correcting sharpness and flatness: https://www.30daysinger.com/tutorial/key-to-perfect-pitch-and-intonation/1

And here's a warmup routine for improving intonation: https://www.30daysinger.com/tutorial/practice-routine-for-better-intonation-singers-who-struggle-with-pitch/1

Good luck!