You need a radically different approach when taking care of lithops, and that mostly consists of not taking care of them at all!
This might be the most important step to note, and the number 1 reason for people killing their lithops -- stop watering them!
Well, don't water them like you water other plants. Water lithops like they are some kind of uber-camel of the pant world. They simply don't need water every day or every week and sometimes even every month. Last winter we aimed to not water our lithops for 3 months. If they get even a little too much, they bloat, burst, and die. In the summer if they are in a good amount of sun usually watering once every 14 days should be fine, but its still better to look at how the plant looks.
A good way to tell when lithops need water is to see if their top face is wrinkling - if that's starting to wrinkle and cave in a little, then go ahead and give your living stone a deep drink.
However - if the sides are wrinkling, then it usually means the plant is going to 'split' i.e. send out two new leaves that will be a little bigger than the old leaves once they come in. These new leaves will suck the old leaves dry, and at this time particularly avoid watering because the roots have been de-commissioned for the time being. Any water at this time would lead to bloat-burst-die or simply root-rot-and-die.
Give your lithops at least 5-6 hours of direct sunshine (dhoop) every day. If you can give it sun for the entire morning, and then bright indirect in the afternoon, that is perfect.
If lithops doesn't get enough sun, its leaves will start to etiolate and become overly tall and lanky, reaching for more light. Lithops should have a pleasingly compact appearance, proportional within itself.
At the same time, lithops are like icebergs - most of them is under the surface, a clever design that allows the plant to stay relatively cool in even the hottest weather.
However, this is harder to do with a small pot outdoors, so find a place it may have some other plants around it, or a place you can keep it indoors and protected from too much heat. Lithops are prone to going dormant if it gets too hot as a way of preserving themselves until the weather is more amenable to thriving.
The soil mix for your lithops should be mostly inorganic, gritty materials like perlite, pumice, gravel, and so on. Keep organics (peat moss, coco coir, organic compost etc) to a minimum like 10%. Perhaps during the really hot months in Pakistan it's alright to do about 20% organics, but otherwise 90-10 is the preferred ratio of mineral to organic.
We typically use a perlite and pumice heavy mix, with some coco coir and organic fertilizer in a 85-15 ratio, and found that our lithops stay happy enough whether its summer or winter.