My own advice would be to not pay attention to Renegade/Paragon but to come up with a profile/back-story for a Shepard that might lean more one way or the other. Do not think of it as yourself making the choices, but the avatar of the character you have created. For instance, you could pick the Ruthless background, a Shepard that will do what it takes to get the mission done regardless of personal feelings. It is Ruthless-Shepard that kills Wrex on Virmire, not you. It is Ruthless-Shepard that kills Mordin on Tuchanka, not you. (And since you have probably never killed Mordin, let me just say that that scene is extremely well done. Very dramatic and filled with feelz.)
Most of my Shepards end up almot 50/50 in the Paragon/Renegade department. Tristan Shepard, for instance, got the paragon version of the Shepard VI dialogue towards the beginning of ME3, but after the coup got the renegade version because of some choices he had made in between.
The one thing about going 50/50 however is that you will want to glitch up your renegade and paragon points in ME1 so that you can max out the number of these points you import into ME2. I always try to import the maximum of 190 points each so that I can pass persuade checks without focusing on being either pure paragon or pure renegade. This also allows me to skip persuade checks and interrupts if I do not feel they are appropriate for the Shepard I am playing at that time.