I find flush rivets on painted aircraft do not generally show very much. So I generally don't worry about it.
On bare aluminum finish, I sometimes make them by applying them with a different color/shade of aluminum by daubing it on with a sharp toothpick end.
For non-flush rivets, one can daub on tiny spots of white glue (again with edge of sharp toothpick or a small piece of wire. Do this over the primer before finished painting. I sometimes mark a rule, a regular pattern, on the edge of a piece of card stock to get the regular spacing. When painted these drops will look like rivet heads. A lot of work though.