Having spent hundreds or even thousands on a personalized registration number many people put very little thought into how to fix the physical number plates to their car if this is not done correctly the appearance of their pride and joy can quickly go downhill. In the past, number plates were drilled and fixed to the car with self-tapping screws, with the advent of plastic bumpers and double-sided tape plates are now usually stuck to the car. Both methods have advantages and pitfalls which will be discussed here. Drilling the plates and fixing with screws gives a good solid mounting but sometimes the screw heads can alter the look of the registration number if they land close to or in a digit, also water can seep into the holes and separate the reflective and acrylic over time, ruining the number plate. Before deciding to drill, work out where the screw heads will be and if you do drill, start from the front face and stop just as the drill breaks through, then flip the plate over and drill from the back, this will prevent separation of the reflective from the acrylic. To ensure that the plates are level and positioned correctly tape the old plates over the new ones and drill through the holes in the old plates to mark the positions on the new ones.
If you do find that the screw head has gone through a digit, a touch of black paint on the screw head will improve the appearance, if the screw heads to land in a blank space, there are available screw head covers you can use so they blend in with acrylic, these are available in both white and yellow for front and rear number plates. You can also get white and yellow plastic bolts and nuts although these are less useful on the new style integrated bumpers and valances used on modern cars.
The main problem with sticking the plates onto the car is one of them falling off! The trick here is to thoroughly clean the surface where the plate is going and de-grease it with a solvent, then use a reputable make of sticky fixers and use lots of them they come in packets and you may as well use them all up.
There is a third option, you can use mounting frames, these are screwed to the car and then the number plate clips into the frame giving the advantages of both systems of fixing, if you change your car often these would be a worthwhile investment as you could keep your plates when you sell the car and transfer them to your new car when you transfer the registration number.