egg whites

chicken breast

tuna

Protein Supplement mixed with Skim Milk, turkey in general, Sea food is usually pretty good also.  The key is getting the most protein for the least amount of calories added, tuna is probably the best food that can do this for you. 

Dry curd cottage cheese has been my answer when upping protein. For 1/2 cup, there are about 120 calories and 20+ grams of protein. Plus, it's low fat and barely has any sodium compared to regular (wet) cottage cheese. For an added punch of protein, sometimes I mix in a scoop of whey protein.

I'm still at 50-60% carbs but I'm keeping my proteins high with egg whites (very recently), beans every day, once a day and protein powder (Designer Whey). I also eat tuna several times a week and either hamburger or chicken daily.

I'm  keeping my carbs almost entirely whole grains with the exception of taters several times a week and rice several times a week.

Whole grains and beans keeps the daily fiber high.

edited to add, I'm drinking kefir and/or eating greek yoghurt (Trader Joe's brand) that's fat free.

When I was increasing my protein intake I usually ate

Egg Whites
Pinto Beans
Boca Burgers
Turkey
Chicken
Protein Bars

almonds
peanuts
beef jerky (my personal favorite)
chicken