in pakistan it is very easy to start a business but difficult to grow it. however, the 4 sectors that are growing like crazy right now are
1) real estate. we bought a portion in ramzan and already the price of that property has grown by 15% in just 3 months. If you are in karachi and have investment then buy any property in decent location and you can safely sell it for 20% profit within 1 year. if you dont have investment then start a brokerage and sell properties to overseas pakistanis.
2) construction. since their is gas and electricity load shedding I suggest you do not start any machine stitching or embroidery unit. Instead you can jump into construction. Just go to DHA and setup shop because over there every 5-6 home has construction/renovation going on
3) restaurant. in pakistan people dont have many avenues for entertainment. cinema is making a comeback but things like theme parks, museums and zooshere are few and far between. so the only entertainment left for people is shopping and food. This means demand for restaurants is sky-high
4) UPS/generator. load shedding is here to stay for another 10 years so now is a good time to start selling imported or locally manufactured UPS and generators. Every shop and household is a potential customer so all you have to do is setup shop in densely populated area and people will come to you.