for flickr groups, if you go to your photostream, look at the titles across the top and click on 'groups', then search for group, then basically type in any key words which describe your work, ie sewing, craft, felt, buttons etc, then the search will give you a list of groups associated with that subject. then you just need to join the group, then if you click on any one of your own photo's, there will be a send to group icon at the top of it, this opens up a list of all the groups you are a member of.
alternatively, if it's sewing groups you are looking for, if you go to my profile, below that there is a list of groups i've joined, just surf around those and join any that catch your eye.
without a pro account, each image can be in up to 10 groups, but flickr is a fab way of getting your stuff seen and you can gauge by the number of views/comments how popular something is, which generally translates into how popular it will be on somewhere like etsy as its a very similar audience.
hth
right, i'm off to do something about my unsightly roots this morning!