Hey,

The scholarship to study abroad comes from merit and the merit is decided on three factors:

Academic Performance, Test scores,Skills related to the subject of interest.It also depends on the country where you want to go.

Most of the universities do not conduct any specefic scholarship exam as they select students and offer financial support to them based on their performance in exams like TOEFL,IELTS,SAT etcetera.Plus,they check your overall performance and resume.So make sure that you are having spectacular academic performance or extracurricular activities.

There are few scholarships that are offered to help students study abroad after 12th for instance-

1.British Council -It offers around 370 scholarships worth 1 million pounds to aid students dreaming to study in UK.There are 36 UK universities participating in this program and offers around 260 undergraduate courses.

2.There are certain community groups that encourage and support exceptional 

members in their academic endeavours.For example:The Harvey Fellow program which aid christian students pursuing graduation at premier universities.

3.Rotary Global Grant Scholarship programs which supports graduate level international study.

4.QS Undergraduate Scholarship

5.Great Wall Program

6.Clarendon Scholarships at the university of Oxford

7.Tata Scholarships for Cornell university 

Apart from these there are other scholsrships offered by  universities in  Australia,USA,Canada and many more that you can get on applying for different courses in their countries.

Hope this helps.