I don't know what your current diet (meaning what you consume- not a "diet plan") is like these days. But what works for me when I start to put on a few unwanted and unintended pounds is to try to up my H2O intake (not flavored or "diet" waters, just plain water out of the tap on ice). Start out the day (even before a cup of coffee) drinking 6 or 8 oz of water. Then throughout the day, before I eat anything (snacks, lunch, dinner, whatever) I try to remember to take a few good deep drinks of water first. If I can, I have a full 6 or 8 oz again. Another HUGE factor, first thing in the morning, eat some protein. Instead of cereal, toast, bagels, etc, grab a handful of nuts (I like almonds) or a slice or two of cheese (I get the hunk cheese from Walmart- Colby is my fav). If you have the time, fry or scramble an egg or two (or eat a boiled one that you cooked yesterday). Not getting sufficient protein in your diet will keep you feeling hungry and wanting to snack. A single egg has about 6 grams of protein, and 1 oz of cheese has 7 grams of protein. If you start the day with some protein (at least 10 grams; 15 grams is better), you will eat less all morning. Same with lunch and dinner, be sure to eat sufficient protein (about 20 grams per meal), and eat the protein part of your meal first. If you do, you will feel satisfied sooner and eat less "junk" (bread, potatoes, chips, sweets, rice - processed or refined carbohydrates in general).
Keep yourself hydrated with plenty of water at mealtime too. Skip the soda, sweet iced-teas or juices... after a short time, you won't even miss them.
Small changes that you can stick with, and that won't break the grocery budget are what are easiest to maintain for the long haul. And that is the best way to lose, slowly...
Change your habits. Don't "go on a diet".
I wish you a Merry Christmas and a healthy New Year!