Hey,

Solving old papers will definately help you score good, but you need to understand the questions when you solve them. Learning the tricks and shortcut methods will be very useful. This will help in solving Aptitude questions quickly and save your time. You can refer to good Aptitude books or else, you can find many YouTube channels from where you can learn these things.
The Aptitude part consists of logical reasoning, verbal ability and quantitative aptitude.
You need to study and improve your vocabulary for verbal ability. This part makes scoring full marks a little tough. Also, logical reasoning will be easy only if you have good practice as it requires you to use your brain. Quantitative will be relatively easier because there are only basic formulas in it.

Hope this helps!