Mass Effect 3 General Reputation, Paragon, and Renegade
While there are different ways of dealing with problems in Mass Effect 3, Commander Shepard will always be a "good guy." He will do whatever it takes to save the Galaxy from the Reapers, no matter how high the cost may be. In Mass Effect 3, both Paragon and Renegade return. Paragon is dealing with problems, choices etc. in a positive way. Renegade, on the other hand, is dealing with situations in a more negative way or ruthless manner. New to Mass Effect 3 is something called "general reputation." Commander Shepard is known quite well around the galaxy due to his past experience dealing with Saren and the Collectors in previous games. What you say has a strong impact on people in the Galaxy.
For example, Commander Shepard runs into a man disputing with a shop keeper in the Citadel. The man is asking for a refund, but the shop keeper is denying him a refund. In this scenario, you can interupt the conversation and side with either the man asking for a refund or the shop keeper who is getting hassled. In my game, I chose to side with the man asking for a refund. Since Commander Shepard's word weighs heavily in the Galaxy, the shop keeper changed his disposition and gave the man a refund -- the man was very happy. There are many other instances like this on the Citadel as well. You gain general reputation points for doing these.
Gaining Reputation Based On Actions by Commander Shepard and in General Conversations
Reputation can also be gained by having certain conversations with your crew members aboard the Normandy ship or with other people in the Galaxy. Make sure to talk to crew members often. Sometimes they do not have anything to say, but at certain parts of the game, new dialogue options may become available.
Much of the reputation in Mass Effect 3 can be gained optionally. I will not spoil too much, but you have the option to visit someone in a hospital on the citadel who is injured. If you visit this person you will gain reputation points for making a visit (neither paragon or renegade, kind of neutral).
More dialogue options will be available in Mass Effect 3 if your reputation bar is higher. Having more dialogue options can be very helpful to resolve problems that you will encounter throughout Mass Effect 3.
Sometimes you have the option to make a paragon or renegade option in the middle of a conversation in Mass Effect. A button will appear on the left side for a paragon option and a button will appear on the right side for a renegade option. Pressing the button for either of these choices is optional, however, choosing one of these may put odds in your favor.
Paragon and Renegade Contribute To Reputation Bar in Mass Effect 3
Your reputation score determines both paragon and renegade options. Paragon is shown with a blue bar and renegade is shown with a red bar on the overall reputation bar. Whether you gain paragon, renegade, or general reputation points, none of them will lower your overall reputation. All three combine to increase Commander Shepard's reputation in Mass Effect 3.