Start slowly and carefully until you’re familiar with each one … then build up until you can repeat them quickly and accurately.
“Sister Susie’s sewing shirts for soldiers
Such skill at sewing shirts my shy young sister Susie shows
Some soldiers sent epistles
Said they’d sooner sleep on thistles
Than the saucy soft short shirts for soldiers sister Susie sews”
“Floppy fluffy puppy” [repeat]
‘An awful lot of offal off an offal lorry’
“Betty bought a bit of butter
Betty put it in her batter
Betty said this butter’s bitter
Better buy some better butter”
“Red lorry yellow lorry” [repeat]
“Peter Piper picked a peck of pickled pepper.
If Peter Piper picked a peck of pickled pepper
Where’s the peck of pickled pepper Peter Piper picked?”
“The sixth sheikh’s sixth sheep’s sick” [repeat]
“I am the very model of a modern Major General;
I’ve information vegetable, animal, and mineral;
I know the Kings of England, and I quote the fights historical,
From Marathon to Waterloo, in order categorical;
I’m very well acquainted too with matters mathematical,
I understand equations, both the simple and quadratical,
About binomial theorem I’m teeming with a lot o’ news,
With many cheerful facts about the square of the hypotenuse.
I’m very good at integral and differential calculus,
I know the scientific names of beings animalculous.
In short, in matters vegetable, animal, and mineral,
I am the very model of the modern Major General”