Before taking your car in for an MOT there are some checks that you can do yourself to try and eliminate some of the causes of a failure. Light bulbs are checked during the MOT, so take a few minutes and check round the car to ensure all are working. Also ensure that your washer fluid is topped up as this can cause a car to fail.
Tyres are one of the most common reasons for a car failing its MOT. If you leave it until the test to replace them you may end up paying more for the tyres than you could have should you have shopped around and if the car fails once the MOT has expired you cannot legal drive it on the roads so cannot take it elsewhere without getting it recovered.
You cannot always know about everything that a car will fail on but fixing the smaller issues can save you time and money when it comes to the actual MOT test.