Man suit is probably the most expensive item in your wardrobe. Usually we are planning to wear our suit for at least a year, but it is important to keep the suit in its primordial condition or close to it, as it is a capricious piece of clothes and needs certain care and following conditions of wearing.
Try avoiding filling the pockets of pants and jacket with all kind of staff: keys, change etc, holding your hands in pockets is also a bad habit. This will lead to straining the seams of the suits. Also you pockets will be stretched and stick out even while being empty.
Don’t forget to unbutton your jacket before sitting down, if not you will be pulling on it. Also it is important pulling pants up just for a little bit while sitting down so they don’t get stretched on the knees and form bulges while staying straight. Also following this principe you will feel more comfortable sitting in your suit.
Before storing your suit in the wardrobe until the next special occasion to put it on, purchase a good wooden hanger especially made for suits, hand your suit only on this hanger and cover it with breathable suit bags for protection from dust and moth. Try to avoid stuffing your suit between lots of clothes, it will make it wrinkle.
You can dry clean your suit yourself as needed with a barely wet rag. But I would advise you to use a bristle brush: brush your suit every time you take it off, it will keep it clean and looking good.