After joining Google+ you started to follow quite a lot of interesting people, created circles and organized people based on interests. Of course you will! Google+ is one of the best place to find cool and interesting people who share quality content and share values.
Now as you start to follow more and more users, your main stream gets flooded and there is a greater chance of missing the content you want to focus on immediately.
The next thing you do is, look for better control of main stream which gives good handle and preference of one circle over the other. For example: family, friends, colleagues, etc.
Luckily Google+ comes with a built in main stream filter that gives fine tuned control of what circles you want to see more often than others in your main stream (you can still select a particular circle on the left sidebar and read all the content shared by that circle without any filtering).
Google+ stream filter by circles
There are 4 different filter settings available for every circle as outlined below,
Show nothing from this stream in my main stream : this setting allows to turn off content completely from a circle from appearing in your main stream
Show fewer things from this stream in my main stream : this setting allows to show few things randomly from a circle