@needlewoman, I’m still fairly new to making clothes and sewing in general, but a walking foot really reduces the intimidation factor in sewing knits. I have a generic walking foot (cheap on Amazon), and it and my 30 year old, 2nd hand machine (no special stitches) can tackle knit sewing just fine. Add in a double needle for hemming, and I’ve gotten really nice-looking results with the Field Trip t-shirt.
Another nice bonus with knit sewing for children, especially when you’re just learning to do it, is upcycling! I make a lot of my 10-month old’s clothes out of my husband’s old shirts, nice knits from thrift stores, or fun graphic tees from woot/uneetee/other online shirt sellers. So if I screw something up, I haven’t wasted a bunch of money on fabric.