Yes. You need to build an audience. You can do this in a variety of ways, but start finding other people in your niche and engage with them. Their followers (people in their circles) will see your comments, etc and if it's interesting enough will follow you (add you to their circles, etc).
By not being spammy. I know that sounds silly, but stop trying so hard to sell, make a friend, be friendly, talk about the weather, take an active interest in what they are doing. The goal initially is not to sell anything, but to be so interesting, helpful, knowledgable or whatever so they add you to their circles. Once they do that they see your posts in their stream.
Post something nice and useful stuff from your google plus business page. I am posting quotes with images and followers really attracts it very much and often share it.
Many advertisers consider Google plus as a great to take a lead. On my personal opinion, since this social network is not that crowded yet it is quite impossible for a certain business to take the edge unless the business had already several connections on Google plus.
I also kinda feel like Google Plus really isnt up to par yet. I dont know, seems like different things work for different people.
It's all about making a connection with your Circles. You need to provide quality conversation, and this includes commenting on and partaking in their conversations too. Just constantly posting a stream of things to your G+ is not enough. As you provide quality conversation more people will continue to follow you and will begin to gain trust in you.
for me i don't really use google plus...it will only generate leads for you if you have a good base of followers which you need to do in lots of ways before your google plus page could generate for you lots of leads...
The community may not be too big right now, but it will become as large (if not larger) than Facebook in the near future and establishing a strong presence from the beginning might give you a HUGE advantage.