I have always thought approaching strangers as a bit forward. During my charismatic days I attempted this a few times but it was very awkward. Most people I associate with know I'm working toward seminary and this often times leads to short conversations that allows me to ask questions and invite people to worship. Since my education is theologically oriented people sometimes pick my brain for answers on questions as well. I try to live a proper lifestyle and just be a witness this way also. Charitable acts, small ones, can be a great way to create common ground and may open up other possibilities as well. I have never used tracts.
Another aspect of this is that I grew up in a couple different cults. I consider those who claim to be christian but are truly errant to be prime grounds for missionary work also. I often engage Pentecostals in theological discussions, and although it has been a good while, I don't pass up an opportunity to invite the Mormon missionaries over when I see them. After a short discussion on why I left the Mormon church I then offer them the gospel.
Various ways I suppose, depending on the situation.
