I was taught the Morse Code as a young man as part of my schooling at a Navy College. The method used then was to group each of the letters according to its composition i.e.
E One Dot
I Two Dot
S Three Dot
H Four Dot
T One Dash
M Two Dash
]O Three Dash
A One Dot Dash
U Two Dot Dash
V Three Dot Dash
N Dash One Dot
D Dash Two Dot
B Dash Three Dot
and so on through the alphabet. Once the groups are put together we chanted them over and over again. i.e.
E I S H One Dot,Two Dot, Three Dot
T M O One Dash, Two Dash, Three Dash
A U V Dash One Dot, Dash Two Dot, Dash Three Dot,and so on.
It must have been an effective method because at 70 years of age there are many things that I have forgotten but the Morse Code still ingrained in my memory.