Let me ask you a question here. How do police solve a murder mystery? What does an investigating officer look for whenever a crime happens?
They call it ‘clues’ and we call it ‘links’ in reference to your question.
Now, let me put you into another situation. Suppose you are a senior Police official in your city and you are to assign either of your two junior officers to solve a case. One of them is quite novice and the other has solved more than 15 similar cases yet. Whom would you choose here to lead the case? Obviously, the latter one.
Similarly, to gain command over problems related to Puzzle Tests you have to try solving a great number of puzzles beforehand to perform well in the actual test. Moreover, your level of comprehension and that of observation must be good enough too. Else, you would end up reading the information given in the puzzle again and again and fail to find the required links.
I would suggest you to start with IBPS RRB Assistant level of puzzles, learn the basics, learn how to use given information as links, learn different patterns and slowly and gradually move up to IBPS Clerk/SBI Clerk level of puzzles and once you become sure that you have gained a sound grasp of solving puzzles, you can start attempting the PO level of puzzles.
The point here is that solving a puzzle is not that much technical and it just needs a thorough practice. The more you do it, the more confident you become about it.
Hope it helps. All the best!