I think there are so many out there and they'll vary lots. I tend to make my own to suit what I'm doing and have optional bastes for each of my hoops including different sizes in different colours (within each) in case I want to do a smaller or larger square, for example. I try to make sure I go a couple of stitches over the start, so it doesn't come undone.

My machine has built in frame stitches and I use the plain one for basting. This frame leaves a cross mark in the center to mark where to put a design or monogram so I try to remember to stop the basting before the cross mark. I can also shrink or enlarge the frame to fit my needs.

Here is a link to a post with more links to free basting stitches. Check them out and and look for one that locks the end with 2 or 3 stitches in one spot or else don't use the "cut thread" function, leave the thread long.

I use a adhevise spray that keeps the material from moving and works really well. I spray the stablizer then put the t-shirt over the top then hoop. They carry it at Joann's I am out and can't remember the name of it sorry.
Dawn

here is another link

NB If you sew on T shirts remember to use a ballpoint needle specialy for jersey knits.Other type sharp needles can cut little holes and cause laddering.
I use a thinnest Iron-on Interfacing Vielene (on the wrong side),before embroidering.Then only pin the corners to the hooped tear-away stabilizer.
Basting is also a good plan but I find the unpicking still shows.
Some ready made T.shirts are over stablized and are uncomfortable to wear.
Also NB try to use designs that are not too dense.
Happy stitching
From Bev

Thank you for posting the basting sites. I have DL them and will try them out. A bit worried as Bevgrift says that the unpicking of the basting shows. It will be a case of trial and error - not too much error I hope. *4U all.

Thought I would add that I have tried out some of the basting stitches and Bevgrift is correct - the stitches for the basting do leave marks, or rather the needle leaves marks. Thank you for all your help.