Just adding onto Nico's answer (with which I agree). It depends on what you mean by "make a stranger notice you." Often, it is appropriate to say "Excuse me" as in "Excuse me - I think you dropped your pen." or "Excuse me - do you know where the train station is?"

In the US, for example, you are in line at Starbucks for a coffee and you want to say something to the person next to you. You would just say hi or how´s it going. But I would not use Mr., Sir, etc. No title, just a quick greeting. Americans often also say How are you? even to a stranger. It´s a bit unusual, but that´s what they do as an informal greeting.

It depends on the reason for wanting their attention. If someone left something important behind and is rapidly moving away from me, I might just use a loud "Hey!" to get their attention. If you are doing someone else a favor, you don't really need to worry about being polite. If the situation is less urgent, I'd recommend "Excuse me!"

In England, we wouldn't use sir/madam in this situation. We just like people to be polite and cheerful! A simple "hello", "good morning/afternoon" or even "how are you?" is a great way to introduce yourself or make passing contact with a stranger.