its depend on how much the electricity fee in your country, what hardware you will use, how stable your internet connection, what coin you want to mine. this is the most important that you need to think before you decide to mining. ok maybe you have cheap electricity fee and you can use vga cards to mining, but you still think what coin that will profitable for you. you can find this in whattomine.com to know which coins that will give you a profit in a day.