When I first played these games, I was almost totally Paragon. Sometimes a bit 'curt' or 'annoyed', but it didn't happen often.
Now, I'm more clearly Paragade. I'm friendly towards my friends, allies, and even contentious neutrals (like Khalisah). However, I don't (nearly as often as before) act kindly towards those who behave as direct threats. You point a gun at me, I'll still hear you out. You point a gun at me and make it clear that you intend on slaughtering me and my squad - you're done. Even if you put your gun down without my influence to do so, I have you marked as a significant threat.
I'd say about 70-80% Paragon and 20-30% Renegade in ME3. I still have to set up my ME2 playthrough on PC, but I was more like 80-90% Paragon last time I played a 'MainShep' there.
I reason this way - if I was in the Krogan Rebellion, I'd shoot krogan with barely a second thought. But with more promising times, I'll try for something, well, more promising. And even when killing krogan in the Rebellion, I wouldn't stoop to genocide of them unless they were in the middle of attempting genocide against us (like flinging asteroids..).
I'm there with the Reapers too. They have to deal with the actions they've done, and I'm not going to rule them in order to have them survive that justice. I'll stay as human as possible, thanks, and take the Reapers down just as my EDI expects, and I believe my geth accept.
My Shepard himself, in some way (even in my imagination), will have to face his own actions as well. I don't put anyone exempt. I imagine my Shepard living in Breath Destroy, but having an honorable (if only due to victory against the Reapers) discharge from the Alliance Military as all the facts of his journey come to light. The good, but also the bad I've had him do.