Meal Planning

I plan my meals the night before, after I've had dinner and am feeling full. I take my schedule into consideration and try to do what I can to get my breakfast/lunch ready in the evenings. Convenience usually wins out over the munchies, so if all I have to do is pop my breakfast into the blender or microwave, I'm more likely to stay on track. Ditto with lunch.

By planning the evening before, I also am able to take a quick inventory of my kitchen and use up my fresh foods first and/or plan a trip to the grocery store.

Mostly, I am able to stay on track by telling myself one day at a time. Junk food will be there tomorrow, if I should want it. Today I am going to eat according to my plan.

I grocery shop and cook on the weekends and then just make fresh veggies during the week to go with whatever I made. I also eat a lot of the same things, so there's not much planning to it. It encourages me to eat out less, altho I do eat lunch out most days. I use the iPhone app to log throughout the day so that I keep up with everything even if I'm away from the computer.

I used to log as I go, but I find it easier to stay within my calories when I plan out my meals including snacks and if I need to change things I will.

If you are using the online site to log, are you making fuIl use of the "Quick Tools" options? For example, I eat almost the same breakfast every day, so I will usually just "Copy from date", pick the most recent one and then alter as needed (delete/add a different fruit usually).
You can also use the "Remember Meal" option, which is what I generally do for lunches because I have about 4 or 5 standard lunches. I will pick one on Sunday and make enough for the work week and I know that's what I'm having every day. So I can just go to "Add food", click on the "My Meals" tab and pick whichever I'm having and all the foods will show up. You can adjust amounts or delete things if you've somehow altered the meal this time around.
Snacks are usually only one or two foods for me and easy to log, so I log everything up through my afternoon snack in the morning before I leave for work, leaving dinner open-ended in case anything unexpected comes up during the day or I get inspired to make something in particular on the way home. I don't have a smart phone, so I find this works best for me most of the time.
I think you are totally on the right track though. I once read that weight loss is an exercise in logistics and I think that's really been true for me. When I have a plan, everything's fine. And since MFP remembers what you use most frequently or most recently, it gets easier as you've been on longer and develop patterns and favourite "go to" things.

What works best for me is planning! On a Thursday / Friday I sit down and plan out on a laminated sheet the main meal for each day of the next week starting on the Saturday and from there I then write up my shopping list. The meals aren't set in stone and I do change them around if I need to. They are mostly the same sort of thing each week and I base them on how much time I have each night to cook and prepare dinner. Like on a tuesday night I do an aqua class and don't get home till 7pm so we have pasta and a veggie sauce which is quick and easy.

I write up my food diary on MFP the night before and just tweak it during the day when I am at work. I am lucky enough to be able to access it online at my desk and I find this helps focus me a bit more.

I do try to batch cook, most of the time there is just 2 of us at home so I cook a chilli and freeze half for a night when I need an emergency meal. It is always best having something quick to hand for when you get the munchies!

Hope this helps!