Segol, which is the vowel under the Alef in - has the sound of eh, as in the e of "hello." Usually when we write this in the English Alphabet we use the letter "e."
That's basically the sound of the E in bed.
What's the memory trick for ?
Well, they kind of look like eggs:
Now, let's practice this vowel in a nonsense word.
"Beg" of course doesn't mean anything in Hebrew, but if we add another letter and a vowel, we have...
beged ...which means clothing! As in a piece a clothing. A shirt is a and so is a skirt.
Next, has a not-quite-identical twin...