My diet tip: All things in moderation.
I find eating healthy becomes a burden when I ban certain foods. So instead, I allow myself to eat anything I want -- just not often. Nice thing about this is that when I do eat it, I enjoy it more -- no guilt, and it's special, so I pay attention to it and make it a reward. Then I find healthy things I like, like fruit, and add them to my diet.
Another recent idea: I use Hassle Me. I have its "hasselbot" set to send me a reminder every three days: "Eat healthy today." Then I try to be extra mindful that day of what I eat.