Speak with Strangers as a Tourist
During my trips, I recognized some friends of mine do not prefer to ask questions to strangers. They are more happy when they struggle on their own. However, I prefer to ask people all the time. Especially, if I do not have the Internet connection. Additionally, if you are practising to learn a new language, this would be the best way to do that. They generally help you out and even though you ask so many stupid questions, they are quite understanding.

So, who should you choose to ask question?
Actually, it really depends on what you are going to ask but I always go for a group of people because it increases the chance at least one person in the group knows where or what you are asking and in case the one who explains tell you something wrong, the others correct them. It is quite useful. For example, if you are standing on your own, in case someone approaches you to ask yous omething you fill more uncomfortable at first side and depending on the person this awkward situation ends quickly when they understand you are foreign.
How to Approach Locals
Every culture has their own way of communicate. This is the reason why learning culture and especially personal space difference makes you job much easier. The classic example would be Brasilian people like to have close connecion but European people prefer to stay away like Asians. Brasilian people may find it offensive if you stand away from them. So, be aware of that and get closer how much the culture acquires.
It is always good to go further from your comfort zone because it will challenge you and teach you new things.