The most important thing to be able to get a visa either a tourist visa or business visa is your passport.some nationalities don’t even need a visa to go to many countries such as citizens of switzerland( and most of european countries), Australia, UK, Korea and America and for example getting a visa for nationals of some countries is rather difficult for many countries even for a short visit for example: Afghanesian, Iran, Nigeria,Syria, Pakistan and Bangladesh.
so the first thing you have to do to get a visa is to check at the nearest embassy( or counsulate,…) of the destination country that wheather you need a visa for that country or not.
some countries such as Indonesia, Maldives, Malaysia and Srilanka need no visa when you want to visit or they will give you a visa on arrival. This is to promote the tourist industeries in these countries.
some times you can check if you need or dont need a visa to visit a country just by searching the web site because most of the embassies now a days have an up to date web site. you can go to visa section or counsular part to check for the visa requirment.
the second thing you need to do is to note down the requirments and download the forms.if you could nto get the forms online most probably you can contact a travel agency and check if they have information regarding the visa forms or not. some travel agencies can get you a visa with a small processing fee and they also can guide you through the documents you may need for application.there is a chance to get a group visa if you are traveling in a group.for this kind of visa you shall apply at a travel agency.
the third thing is : read the instruction of the application form carefully before filling the forms for example if you need to fill some or whole parts in BLOCK LETTERS or with a black pen.
for some countries or for some special kind of visas (for example a business visa) you may need extra documents rather than the filled application form and passport size photos. proof of business for example the companies registration documents or official newspaper where the companies existance is advertized. or you may provide proof of financialy support for example your income slip , bank statement or support letter from the company you work for or the university or institute you study, return ticket from and to your original country, hotel reservation in the destination country.