While attempting to lose fat, what's the best way NOT to lose the good stuff? Is the secret to do cardio and lift weights, keep protein intake high, and move lots of water? I eat a very clean diet, 6 small meals per day every 2-3 hours. I am 21 years old, 6'0, male, 159lbs. I won't make a big long post of my diet and make for a bunch of reading, but I'm getting ~1700 calories per day, ~112g protein. My current weight is now what my lean weight was before I started. I've seen good fat loss, I seem to be in the 11-12% body fat range, but would like to shave 2 or 3 points off of that. Any advice?

To preserve lean body mass, I would say you should increase your protein intake to approx. 1 gram of protein per pound of bodyweight. But 1.5g is better. 1700 kcal/day is not that much if you train hard, and adequate protein intake can prevent muscle loss arising from heavy training and low-calorie intake. Weight training is very important, just ensure you don't over/undertrain, your body gets enought time for recovery, and plenty of nutrients. Have a protein shake and dextrose tablets post-workout.

Wow, that much protein eh? You guys favor protein shakes over additional servings of like fat free Cottage Cheese? Any brand preference on the shakes and tablets?

I have a whey protein shake when I wake up in the morning, and another one post-workout. These two provide me 20+40 grams of protein. Another 190g is consumed during the day in the form of chicken breast, fish, lean beef, low-fat cottage cheese, eggs, and soy. So you can see that I consume 250g protein every day. I supplements as supplements only. When I don't have the chance to eat wholesome foods, I drink a meal replacement product.

I personally prefer MetRx and Prolab but NitroTech is also good. I don't think there are huge differences among these brands, it's more about personal taste, preference towards brands/personalities advertising the product, or price.

Glutamine will also help to preserve muscle. ~20 g/day. Best taken in small amounts throughout the day if possible, on an empty stomach.
Also, 1 can of tuna can add 37g protein. Easy, real food.

What if you're mainly doing cardio (running)? Should I still think about protein shakes/supplements? I'm 5'8 148lbs with 13% bodyfat.

If you want to maintain your lean muscle and are not hitting the mark on your daily protein requirements, absolutely. If you're not losing muscle, then you shouldn't have to worry about it.