Most of the students are struggling to understand or memorize the 12 Major and Minor Keys. So I have created material and talk about it. It included the key signature that was shared with the same relative minor/major key.
The column in between the major and minor key is the key signature.
We can start on C major (no sharp no flat), and start our journey from there. To find a relative minor key from a major key, you have to move to the left 3 semitones, for example, to find G major relative minor, G < F# (1) < F (2) < E (3) = E minor is the relative minor key of G major, and reverse order to find the relative major key (move to the right 3 semitones), From E minor, E > F (1) > F# (2) > G (3) = G major.
Next, to find a new sharp major key you just have to move to the right 5 steps, for example C major > (C,D,E,F,G) G major > (G,A,B,C,D) D Major, etc.
To find a new flat major key you just have to move to the left 5 steps, for example C major, (C,B,A,G,F) F major, (F,E,D,C,Bb) Bb major, etc.
Hope this clarifies your confusion. Let me know anytime if you have any questions! Happy to discuss this with you! =)