The best snacking advice I can give is to buy produce such as carrots, celery, etc and get some snack size ziploc bags. Wash and cut up the produce and put it in the bags, stick them in the fridge and whenever you need a healthy snack there they are.
I pack my lunch each night, usually when I'm cleaning up from dinner. That way, when I'm rushed in the morning, I can't forget to make a healthy lunch.
The best thing I was ever told was to think of my calories as a budget. Know how many you can have each day and before you eat something ask yourself if you can afford it. If it's worth the amount you have to spend and you have the calories eat it if not rethink it.
Bad day? Blow your calories? No problem. You can push the reset button anytime. If I've gone off track, whether it's for a month or a meal, I literally stop, take a moment to breathe deeply, and imagine myself pushing a giant RESET button. The image lets me release what I've done and move forward.
....is key, make sure that you don't deprive yourself!
Drink lots of water. It keeps you full and I find that sipping it through a straw keeps my mouth busy enough that I am not looking for something to eat.
My secret of maintaining my ideal weight over a long period of time has been , small portion size, avoiding deep fried food , and brisk walk 6 days a week without fail.
I carry a bag with two bottles of water in it .... it is like carrying lil weight with you especially when climbing the stairs.
When i have a non diet day, i always have a special treat, which is either, cheese on toast, or melted cheese in microwave, these are nice with a large mug ot tea.