I am approached by strangers frequently and asked out. Also have been approached when online that they have seen me. Its no big deal. Just use your common sense. You are going to get weird ones but have met some normal people who at the end of the day just like you and want to be friends. Your going to have a hard time in life in you don't open yourself up to meeting new people. Whether for friends or more. Enjoy it.
Last year, I saw a lady at a kiosk at the mall. She was buying perfume, no ring. I took a chance and said Hi, I am XXXXX, can we go over to Starbucks and have a coffee? Bingo, it happens.
I do it all the time. In fact I did it this morning at the gym. It always works out perfectly.
I have approached strangers for several reasons ( asking time / directions when I am traveling /addresses, etc ) but never to flirt. I can´t flirt to save my life.