Shipping Rates from MA for home decor store!

Hi,

I have a home decor brick and mortar store and an online store at shophomeacton.com. I have yet to get the shipping rates correct for the online sales, and could use some help! Although I sell furniture, I just want to start really small for shipping and make sure I have that right first! Right now I’m losing money on shipping and need to put an end to that. The items that I can ship are small pieces like jewelry, pillows, cutting boards, candles, baskets, door knockers and small pieces of art. All of these items are 10 pounds or less. The confusing part is that the smallest jewelry pieces are the lightest but the greatest value. I would like to use either USPS or UPS (I have an account). What is the simplest way to figure this out? By weight? By price? And then there is destination… everything shipping from Acton, MA and will ship to USA only. Shopify is asking for a standard box to base prices on, but there isn’t one size fits all. Help!!!