Chat on the warm-up
Compliment good plays/serves
Racket Clap a great winner.
Laugh at the end of a funny exchange.
Chat on change overs...mostly about work.
I have been part of the design
team for most of our local medical facilities along with plant work that 50% of the time I am playing someone who works in a building I helped build and often come away with some great future job contacts.
If it's someone I know well I will throw in the basic joking smack talk. like "Oh someone went out and got a big boy serve?" after getting aced.
and Amoung my team mates during practice we will do impressions of each others service ritual just to mess with each other.
I have had a few silent opponents...and I don't push the conversation on them...but I play for fun.
as far as game play - I am quick to give first serves for delayed time because of the next court knocking balls into ours etc.
I feel I am probably to fair on calls (often hitting out balls back into play)
I'll hold a 3rd ball for the server in my pocket so he doesn't have to chase one down.
I'll keep up with the score board on change overs.
and I typically carry extra water/salt tablets/ibprofin/band aids etc in case opponent (or doubles partner) needs so medical help.
I have had an opponent that turned his ankle and had to retire..but before he left (we gave him water/ibprofin and an ankle brace) and my doubles partner who is a doctor checked it out for him and made some suggestions.
Had another opponent cramp so bad I actually carried him off court to the tournament recovery area where they gave him water salt..and the medic worked on massaging the knots out.
and my favorite thing to do (I speak a few different languages and when I run into others that speak them as a native I really like to get some practice in and possibly learn some new stuff)
probably what i like about tennis most is the culture of the people you meet from indians/asians/europeans/Latin etc..