Probably you have had that exasperating (yes, I looked that one up in a dictionary) experience, too: Bought a (rather expensive) quality T-Shirt, wore it a couple of times - mysteriously the first hole appears, followed shortly by 3 others as the weeks go by. So you prepare yourself to degrade the shirt from favorite to garden- or night-...

...or you prepare yourself for some rainbow sparkle... here comes the Shirt-saving Rainbow-Repair (with lots of pearly rainbow shimmering sequins - the pictures don't do them any justice...)

Supplies

shimmering rainbow sequins - I usually by the ones on a string - since they are easier to get in my area, and bonus: They are less annoying to work with! (Since the cannot spill on the floor or blow away or get electrostatic attracted to you in great masses... just pull of the thread one by one as you need them)
scissors and a needle
hand sewing or embroidery thread in a color, that matches your shirt
optional: a hand full of chalk stubs or other small, linear objects
(T-Shirt with small holes to mend)

Step 1: Add Some Random Beauty...

While it is quite clear, where to put your sequins in order to hide the mended holes, the positioning of the rest of them is a design decision:

Use a hand full of chalk stubs to determine the places for the additional sequins and to add some randomness:
Gently throw them on the shirt like dice. Were they land make a linear mark with the chalks - see picture.

Step 2: Mending and Beading (or Sequining?)

Mend the hole by sewing the edges of the hole together with whip stitch.
Cover the mended hole with a row of 3 sequins in back stitch.

Step 3: Keep Adding More Random Rainbow Sparkle..

Cover all chalk markings with a line of three sequins, as you did before with the mended holes
On the back side tie double knots and leave a long thread tale!
Admire your "as good as new" favorite shirt...

Have fun!