how to improve my aptitude skills?

There is no shortcut to improving your aptitude rapidly. It is a slow process and requires time and practice. Below are some useful ways to improve aptitude-
1. Play Sudoku in the newspaper regularly

2. Try to think beyond the limits 

Try to generate things in your mind which are not exist, like fish with legs, etc

3. Play puzzles on the internet, there are many sites available which offer good puzzles. 

4. Look up questions on the topic from previous year questions paper of various competitive exams.

5. Give an online mock test as these tests are designed to assess your verbal, numerical & logical reasoning performances and it will increase your self-confidence.