I don’t know what is the most profitable business idea for your country, but in Europe, the latest trend is buying a property for daily rental income through airbnb.com and the similar websites.
Short-term rental of apartments can bring in 2-3 times more than renting the same property for the long term. This is especially true for large cities, because the main contingent of tenants — tourists or business people— are not willing to overpay for a hotel room.
There are 3 ways to start this business:
you can rent an apartment for a long term, and then rent it for short-term to subtenants;
to rent your own apartment in the city centre, taking a cheaper one on the outskirts of the city;
Buy an apartment on credit, rent it out for paying the mortgage loan.
To earn money from the offline business, you have to look at the competition in marketing. If you feel that there is more demand for that work then you should invest money in that business. A business should be open in which competition are less and demand is high. you have to see it around you.