What intervals to learn for EAR TRAINING GUITAR AND VOICE?

Question:I'm doing this exercise where I record a note and then I try to sing the major 3rd. I record a bunch of random notes then try to sing the maj 3rd. My question is: What interval should I work on next? Should I work on the minor third? I know the maj 3rd is important in harmony, but I am still new to that kind of stuff.
Thanks.

Best Answer - Chosen by Asker: I'm doing this exercise where I record a note and then I try to sing the major 3rd. I record a bunch of random notes then try to sing the maj 3rd. My question is: What interval should I work on next? Should I work on the minor third? I know the maj 3rd is important in harmony, but I am still new to that kind of stuff.
Thanks.

Try these intervals next -- major 2nd, perfect 5th, perfect 4th, then a major 6th. Major and minor 7ths are much harder.

i would try perfect 4 which is one note higher than major 3rd

or you could try doing solfege in c major
its a simple way to learn all the intervals at a fast past

for example
do to the same not do is unision
do to Re is a major 1st
Do to Mi is a major Second
and so on.
hope this isnt too confusing