Santa Teresa & How to Tip

We were just walking up the street after having a nice little lunch near the park. Suddenly there was another awesome ruined church. I was taking photos through the iron gate and wishing I could get inside to see more when the caretaker arrived. He invited us in, said it was ok to take pictures and told us about the history of the church.
This convent and church were built from 1677 to 1687. Originally housing 3 nuns from Lima, Peru, the convent ultimately grew to 18. The 2-story building was badly damaged in the earthquakes of 1717. Some 20 years later the convent was restored. Then in the earthquake of 1773, it sustained extensive damage again. The impressive façade of the convent survived all the earthquakes, including 1976. The northern section of the building still stands and now houses the city jail for men!
I asked our friendly guide if he had been in Antigua and remembered the earthquake of 1976. Yes, he said, it was horrible. Actually the first one, on February 4, happened at 2 o'clock in the morning. The second one occurred on February 6, during the day, and was terrifying. When you see the enormous pieces of buildings which are now lying around on the ground, you get a feel for just how terrifying it must have been. The 1976 earthquakes left 23,000 dead and a million homeless.
I often marvel at how the people here seem so proud of the ruins, and want to tell the stories to outsiders. I am embarrassed to call a ruined building " beautiful," although of course they are. I'm not sure exactly how this works, but my feeling is that they are proud that they survived, and that their city is still one of the most impressive and beautiful cities in the world.
As we started to leave, our informal "guide" told me that it was "customary" to give a small "propina," or tip as a thanks for the information. This seemed totally reasonable to me, but I was embarrassed that I had no idea what to give. We gave him 10 quetzales and he seemed satisfied with the amount. Chiqui later told me that while it certainly is not required to tip such "informal guides," if one wishes to do so, 5 or 10 quetzales is considered adequate. So I think next time I will try to have the cash in my hand, ready to give when shaking hands good bye and thanks.
So many things to learn. Cultural differences are fascinating but bewildering. I have a tendency to not want to embarrass someone by offering money inapproprately. I guess it's better to offer it, but to do so in such a gracious way that it won't be considered an affront if offered at the wrong time to the wrong person. Much easier to do if fluent in the recipient's language. Another reason to keep studying!