Start with having good work. Go and paint as many paintings as you can so yo will become good at it.Than approach galleries enter juried exhibitions, give some work to charity auctions.
The cafe or restaurant thing is overrated, no waiter has the time or knowledge to talk about your work, they don't get nothing for selling your work. They try to earn their tips not to sell your work. Also get a web site you can get a free one in the beginning on places like artmajeur.com that is where I have mine link below.

try doing small exebitions and work your way up