Understand what you are trying to achieve in Groups.
These have members that you might presumably meet at an industry conference. They may include your competitors but also your suppliers and other associates. The value of this group is that you can learn from them, discuss industry issues, be alerted to changes worldwide on legislation, marketing and other practices that you should prepare to take advantage of.
These groups have members who do something totally differently from you. They may be pure networking groups or groups with another focus such as marketing, medical, industrial etc. You may be able to join the group to meet people who need your services.
Open or Closed Groups
The group owner will make it Open (anyone can join with one click) or Closed (ask to join and they will decide whether it is appropriate or not). Also check if they issue any rules about what you can post. Some groups are vehemently against self promotion while others are designed for that option.
Posting to Groups
Start discussions that you believe would be interesting to the members of that group. But also remember to participate by answering other people’s discussion comments. People will feel reluctant to engage with someone who they do not recognize in the group. Links to your own or other online articles can be posted as well as setting up Polls.
When searching for a group, check out their statistics to see how big it is and whether your type of target audience is well represented.
Make strategic connections:
If you find a person that you would like to connect with, and you do not have their email address, then see if they belong to any groups that you could legitimately join. Once you are in the group, find them in the list of members. Hover over their name, (still in the list of members) and it should have a blue background. On the right hand side of the page will be the option to Send a message or Connect with that person. Personalise the message to them, but the title they get will be that you are both members of the same group and you wish to connect.