How to achieve this effect in Illustrator

The brush tool? What application are you using? Those logos are all done in Illustrator. I'd draw it with a pen, on some paper, scan it in and redraw it in Illustrator. Or autotrace it.
As mentioned in the thread title, I'm using Illustrator, and I was referring to the Paintbrush tool.

I'm still an Illustrator novice, and was just wondering if I'd missed any glaringly obvious more automated methods of achieving that style than just hand-drawing the design.

Thanks for the advice, anyway, I'll give Auto Trace a go :icon_smile:
Ooops. That'll teach me to skim read things. You could also try using the pencil tool to draw with if you've got a tablet. Or the pen tool to carefully trace over your original sketch.