I've been doing roving characters at events for nine years - I started by playing Captain Morgan in the bars of British Columbia's lower mainland. Since then, I've been all over the world playing over 50 characters that make people laugh and create fun memories at events. These pics are from my gig last month in Switzerland helping to host a week long event.
1. Have a good costume. It's the worst when your costume is shoddy. First impression has to make the audience want to look at you. Details are key. Try to get a NAME TAG that shows you're with the group. Interactive elements, props, and little gifts to give out make your job easier.
2. Have a good vibe. If you're having a good relaxed time, that joy will spread.
3. Have a few start up lines or puns. This initiates contact with the crowd and lets you assess if they're cool with improvising a little with you.
4. Create in the moment. Based on the reactions you get, let the relationship with the audience member unfold and play for as long as they're enjoying it.
5. Know when to roam. Not everyone loves a roaming character. Be ready to say a quick joke or make an impression and gracefully make a fast retreat. Sometimes being part of the background like standing at a doorway is the best way to entertain and not annoy.
I wish you all the best improvising as a roving character!