Keeping a food journal is my secret weapon. Recording food seems to be a very powerful motivator to eat well because it enforces awareness of what I'm stuffing into my mouth. When I have to stop and write it down, have to think, OK, am I eating this because I'm actually hungry or is it fulfilling some other need? Also, seeing how many calories I've had that day helps me answer the question -- if I see have a big calorie deficit, sometimes it's a green light to go ahead and have a big salad or a healthy snack because I must actually be hungry! It seems to have been the key to all my weight-loss successes in the past.
The trickiest thing is exercise. I often go on 2-3 hour bike rides and I just don't believe the calorie-burn estimates. To be off by 15% for a short workout isn't a big deal, but to be off by 15% when you've burned an extra 2500 calories is a huge difference!
Years ago I used My Food Diary and I loved it for the community. Now that there are lots of free options out there it's hard to justify the subscription and I switched to MyFitnessPal. What do y'all use?