Enter everything you eat honestly and fully. Don't be afraid to see how many calories you ate or how many grams of fat there were when you make a not-great food choice. Many times, I'm pleasantly surprised to see that what I ate wasn't really that bad and that I'm still on track. Often one poor f...
Eat several times during the day instead of breakfast, lunch, dinner. If you plan for five smaller meals instead of three bigger ones, you'll feel full all the time - in fact, you might need to make yourself eat because you won't be hungry yet. But it definitely busts those plateaus!
Lots of people feel obligated to plan and prepare a different meal every day, but it's much more efficient to double a recipe and eat it for two days than it is to cook something new every day. It usually guarantees lunch options that are not "buy fast food" and gives the cook a night off!
Make other goals for your life and put them on SP to remind you to do the little things every day. I have goals to enter my weight, to make time for my partner, and several to get my sleep schedule working better and to get me in a routine. It's just a tiny reminder, but it really works!
Don't deprive yourself of foods you enjoy or insist on a very restrictive (fat-free, low-carb, no-salt, no-sugar, etc) diet. Read serving sizes and budget for the things you love. It's much easier to stick to a diet that is full of foods you enjoy than one that says you can never eat another cookie.
Surprisingly, weighing myself every day has made me less stressed about the ups and downs of weight loss. Seeing how weight fluctuates day-to-day lets me see long-term trends rather than putting all my hard work (and self-worth!) to the test in only one weekly weigh-in.