Looking to build blankie and fullbody onsie where should I start?

Any suggestions? I'm looking fabric that's soft and will stand the test of the washing machine. Where can I buy good prints? what fabric should I buy?

You could check if there are any fabric stores near you, that way you could touch the fabric and see if it feels nice to you. For a blanket it depends on how fuzzy you want it to be, you could go with fleece which wouldn't be overly fuzzy but very soft and warm. There's other fuzzy fabrics, including that one with the little textured knobs all over it, but unfortunately I don't know what it's called. Though to be perfectly honest, it'd probably be easier to just buy a nice pastel colored blanket, they're everywhere this time of year, and much cheaper than if you were to buy the same amount of fabric...

For a onesie, you definitely need jersey, or something similarily stretchy. There are tons of online stores that sell child-like printed jersey. If you want it to be really warm you can look for a sweatshirt material, or french terry, they also come in really cute prints. I usually buy my fabrics locally, but I've seen a lot of the same fabrics in stores and online. Jersey is also definitely washable, though you shouldn't wash it too hot or it will lose its shape.