If anyway you can buy yourself a serger, it is so much faster and way more professional looking. I honestly can't imagine sewing for others and selling it without it...
I'm sortof a nut about having the inside of my garment looking as neatly sewn as the inside. I use a coverstitch for the hems of my knit items, 4 thread overlock for sewing knits and 3 thread for finishing woven items.
I even cover the overlockstitch on the necklines of my jackets (like the one below) with a nice ribbon.
If a serger is really out of reach you could use a french seam which incases the unfinished edge or finish it with a biastape.
http://www.etsy.com/listing/97385453/farbenmix-baby-jacket-unisex-hoodie-sz-3Greetings from The Netherlands,
Denise