A canvas tote bag or similar. Most craft stores sell a selection of these. I chose a messenger bag, because it has side pockets perfect for holding a bottle.
Washable magic marker
Start by pre-washing your bag, but go easy on the dryer. If it's canvas it will shrink a lot if you dry it all the way in a hot dryer.
Then find an image you want your piece to be inspired by. I say that, because it will turn out looking very different from the original art. I googled "hen and chicks" and came up with this image. I'm the mommy hen, and I've got three little chicks! Get it? :) Then, I sized it to fit my bag and printed a few copies out onto regular paper.
Cut out the outline of your image and place it onto your bag. Keep an extra copy to look at while you are sewing. Trace the image outline onto the bag with a washable magic marker. You will get an outline image that looks like this: I winged (hehe) the eyes and wings. You just want a simple pattern to follow, not a drawing masterpiece, so don't worry if yours doesn't look as good as mine ;).
Then, start sewing! Keep to a simple straight stitch. If you want to beef up the color in spots you can use a cross stitch. Don't know if that's what it's actually called, but a stitch that looks like an x. The back of your stitching ain't gonna be pretty, just warning you. Because my stitching is on the flap of my bag, I will probably cover it with a piece of fabric eventually. Hopefully sometime before July when baby comes.
After your stitching is complete, through it in the wash to get rid of your pattern, let dry, and you're done!
Now enjoy your hand made tote!