It depends a lot on what languages you both speak, and what level, of course. As Wersim said - talking slowly is a good idea if you are speaking a language that one of you isn't so familiar with. Also - speaking clearly, and using simple words. If the other person doesn't understand, try different words. Even 'sign language' can often help. It also depends on where the tourist is from, as to whether they will appreciate the chat. Some nationalities are quite open, some are more guarded, so might be unused to talking to strangers. Also - be aware that tourists often have to be very careful of being 'taken advantage of' by locals. By being friendly, you might be misinterpreted as trying to sell them something, or take them somewhere they don't want, so don't be too forceful with your initial approach.

I talk with them slowly