@mashriqain
You should put a large 'L' with red tape (use the insulation tape you use to cover tennis balls to play cricket) on front screen (passenger side) and rear screen (passenger side). The size should be about 6-10 inches. This is not only required by the law, it is useful for you because other drivers will know that you are not perfect in your control of the vehicle and give you more braking/steering margin or even not honk their horn if you stall your engine and can't restart it promptly.
Some people splatter their cars with small red 'L's everywhere but this is a hindrance for the driver especially the learner. The L on the screen should NOT hinder visibility of other things you might need to see.
@ahmedbila
Learn the signs book. It also had some text. Learn it. The test-taker can ask questions like if so-and-so condition happens who will have the right of way?
Plus in Karachi you have to take your own car (in Clifton branch there are agents who will lend you their car for Rs. 40/- or so but own car is better as you won't falter over its controls) and they'll run you through a slalom course (in-and-out of cones, at slow speed obviously, it is not a Porsche test track), make you parallel park, make an L (or a 3-point turn) in VERY tight spaces and you'll fail if you step on a cone, so make sure you know your vehicle. It is better to take some small vehicle you are perfectly comfortable with.
The vehicle should be fit in all respects: lights, indicators and side mirrors.
Remember: use indicators whenever you can.