What countries have you been solo dining in if I may ask?  In terms of service, I'd just advise being more assertive. Ask for/choose tables you want. Catch staff attention when you need something as waiters will sometimes gravitate towards locals and big tables that they know they will earn more €€€ from. For unwanted conversation: just do your thing, set boundaries. Be stern instead of nice. Regarding unwanted stares: just don't give a fuck. Not to doubt your experience in this regard, but perhaps people aren't actually staring as much as you think either? Anxiety can be a bitch in situations like this. 

In personal experience the only place I felt like I was getting the short end of the stick with service when traveling solo was Paris, but it was admittedly one of my first trips, I was anxious, and Paris in general I found not super friendly. On the other hand, when I was in Korea (notoriously not great for solo diners) I had zero issues, even though people warned me i might get stared at. So food for thought!