Probably doesn't matter too much. I go to bars and read books. I'm sure going to a bar and ordering a coffee is less conspicuous and accepted. In fact last year I contracted an eye disease and was on all sorts of medication. I was out at bars drinking teas while my friends were drinking alcohol. Doing slightly off standard stuff like that tends to draw attention and people spark up conversations with you.

I'm sure the main point is go when the staff have some downtime and the business is a social business. I can't remember where it was but I've gone to a cafe for a tea and ended up playing backgammon with some old guys. Many countries seem to have a strong cafe culture where old men sit around playing board games (Middle East and Central America; chess and backgammon).

Best of luck. If you find it hard to socialise now I am sure after travelling for a while you will be much more comfortable with it.