To help others - take what you will from my experiences.
I weighed myself as often as I could, at the same time every day. It seems obsessive, but it's all about what you do with the information. For me it was a way to keep in check - if I was up 1/2 a pound one day to the next, it gave me cause to double-check my eating habits. It MIGHT be just water weight, but it might not. It sucks being tied to the scale - and it's not for everyone - but it's what helped keep me accountable. Also I'm a total nut for gathering data. I logged everything in a Google Sheet - along with measurements, an exercise diary, predictions, and goals - and graphed things like the Fall Challenge and the Winter Challenge (to date.) Seeing everything lined up helps me stay on track. I like data. I like seeing it change for the better.
I took pictures of myself and put them on Facebook. I don't usually do that. The compliments were the best reward ever. I know they say that can be damning - it's a "reward," therefore you're "done" and have no reason to push on. For me it's accountability. People know how far I've come, and if they like it now they'll REALLY like it when I've pushed to my goal. I know it's superficial but as someone who's been very camera shy, it's the best feeling in the world to enjoy yourself - and see others doing the same.
No punishment, man. Learn from everything and move on. I've had my 1900 calorie days (with no exercise) from time-to-time. When I see the scale the next morning I just lace up my running shoes and take off.
Don't assume "you got this" just because you've been logging for a month. Always log everything, if possible.
Never give up. If you've blown your day on fast food and ice cream, it'll be tempting to say "well I'm already this deep down, might as well finish it off with a beer." Any time you have the opportunity to dig yourself deeper into a calorie hole, you also have the opportunity to say "no." It'll get easier each time, and it's rewarding to wake up the next morning knowing that even if you did bad, you still said no to something that would've made it worse.
Make yourself a black list, especially for parties/big dinners/etc. Don't tell yourself "I shouldn't have this," tell yourself "I can't." My personal blacklist for parties/events consists of bread, handheld desserts (cookies), pastas, and anything coated in cheese. Make yours whatever you want, and stick to it.