In a lot of ways it's very much the same as setting up a business page on Facebook, once you've chosen the type of business that you are, you add profile pictures and some basic information. There's a very good explanation here on Craft Blog UK
Then you need to start getting your page known. I have found this bit harder on G+ than on Facebook as I rarely use G+ for personal socialising, so I don't have the same network on here as I do on FB to promote my new page.
So I started by searching on G+ for pages with the term 'handmade' that immedaitely yielded a number of results. So I followed a number of relevant looking pages and then had a peek at who's in their circles, which lead me to other pages.
However, I want to get my page seen by 'real' people, not just other similar business pages... I've not found any miracle ways to get this done, other than starting to use G+ a bit more frequently, link up with more people I know in real life and get them to do some promoting.
I have been toying with the idea of offering a giveaway but I'm wary of them as every man and his dog seem to run them and I think you probably need to have a relatively good fan base initially.
Good luck to anyone else setting up a page and I'll keep you posted about how I get on!
