I work in a gallery/shop where we sell artisan made goods etc.
I've also managed lots of craft shows.
It's a steep learning curve for many people but if you make things which people like, then you can make profit.
A good tip is to check Etsy out for similar products to those which you make and look to see the number of sales each seller has made...you can check their reviews too.
Some things just don't go...for example, I recently accepted a number of cotton shopping bags which I knew wouldn't sell but the owner of the building was pushy because they were made by her sister...they didn't sell at all, as I knew they wouldn't due to the fabric choices.
She'd made them well...lined and neatly done but the prints were very unattractive and old-fashioned (and not in a good way).
What we find sells well, is useful items. If someone sees something they can use in the kitchen for eg. then they can sort of justify the frivolity of buying such a thing.
So, some wooden cheesboards we have...which are etched with mandalas...they go like hot cakes. Well made, well priced....great gift.
As you sew, you could look at bags of course, zipped purses, childrenswear. Aprons just don't go. Nobody uses them and they know they'll end up shoved in a cupboard somewhere.