The major keys with sharps are:
G major (F#)
D major (F# C#)
A major (F# C# G#)
E major (F# C# G# D#)
B major (F# C# G# D# A#)
F# major (F# C# G# D# A# E#)
C# major (F# C# G# D# A# E# B#)
The major keys with flats are:
F major (Bb)
Bb major (Bb Eb)
Eb major (Bb Eb Ab)
Ab major (Bb Eb Ab Db)
Db major (Bb Eb Ab Db Gb)
Gb major (Bb Eb Ab Db Gb Cb)
Cb major (Bb Eb Ab Db Gb Cb Fb)
Tips for Remembering the order
A way of remembering the order of sharps for a key signature is by devising a phrase to remember the letters.
e.g. order of sharps in a key signature is: F# C# G# D# A# E# B#
phrase: Father Christmas Gets Drunk At Every Bar
To remember the order of flats in a key signature, reverse the order of sharps
e.g. Bb Eb Ab Db Gb Cb Fb
For more ways of figuring out key signatures, watch my two videos “The Key To Everything”