When you set up your Google+ page, you should follow the SEO basics you'd use for setting up a webpage or social media profile: use keywords, meta descriptions, page titles and links to optimise your G+ page and link it to your website, landing pages and other content you own, such as blog posts.
Certain G+ pages are signed up to the Direct Connect service which allows users to search for them using Google by adding a plus sign in front of a brand name, for example +Pepsi or +YouTube. So far this is only available to a small selection of brand names, but Google has announced plans to roll the service out to a wider group of companies in the future. By making sure your Google+ page is well connected and regularly used, you can give your company the best chance of eligibility for the Direct Connect service in the future.
Making connections by adding other pages and users into your circles, starting hangouts, commenting on other relevant posts and +1ing content can all help you to grow your audience and following. Remember that Google+ is a social media platform after all - by engaging with targeted followers, you are not only boosting your search engine optimisation but also increasing your social influence.
The +1 button can be added to blog posts, and website landing pages - it also appears in search pages next to results. The link between the number of +1s a page has received and its ranking in search results is not entirely straightforward, and much work has been done to avoid spammers and unethical SEO users abusing this feature.
The more +1s a page or link has, the more likely it is to be shared, and in turn, will receive higher rankings. The +1 algorithm is both social and search-related, which is why becoming active on Google+ is more important than just flooding it with spammy links.
The +1 button works to promote word-of-mouth interaction too, by flagging up links that your friends have 'validated' by +1ing in your own results using Search Plus Your World. If you're not signed in to your Google account, users will still be shown the number of +1s a page has, which can influence click-through-rate also.
Google+ can be really beneficial to your social media marketing and search engine optimisation efforts by increasing search rankings as well as boosting your social reach.