You know what would work much better than standing shouting on a concours? Bill posters.
Last year at the Convention, we stayed - as usual at the Express by Holiday Inn, Perth (hi to anyone reading this who knows us from there. I was the gumpy looking bald one who always wore a t-shirt and jeans to breakfast and never wore a name badge). Right across the road from the front door of the hotel was a very big bill poster (one of the bigger roadside posters) that had a picture of a door, complete with knocker and letterbox. I caught a glimpse of it as we drove into the carpark of the hotel. I immediately thought it was put up there by apostates and it would be something about the JW door knocking ministry.
However, when we'd parked the car and unloaded the luggage, I had a proper look at it. Yes, it was a picture of a door, but the legend read "Jesus is knocking at the door. He just wants to you to answer". It had a big impact on me as I had spent the month or so previous to this researching the WTS teachings, coupled with reading the New Testament. Gail and I had realise that it was all about Jesus afterall.
I pointed it out to Gail, who immediately well-up with tears. It was as if the poster had been put there just for us.
I think similar posters near convention sites, perhaps not just with a Christian theme, would have a greater impact than just standing shouting at them.
Earlier this year we tracked down who it was that placed the bill poster. It's a Christian out-reach ministry in Perth and they were delighted to hear from me.