Begin underneath, grease propshafts and steering ball joints, check rear floor and chassis for rust, check all brake pipes for rust, and flexibles for damage, check all suspension, and exhaust, then all steering and suspension joints for excess play, or leaking shock absorbers, and CV boots for splits if fitted to your model.
Coat all brake pipes with grease to protect them, any rusty ones should be replaced with copper pipes, check all tyres for splits or damage, particularly on the inside, and the tread depth.
Jack the vehicle and check wheel bearings for play, remove front wheels and check brake pads and discs, wash these out with water to remove all brake dust, do not use compressed air.
Check all basics such as lights, seatbelts, windscreen for cracks or chips in the line of vision, washers and all wiper blades for condition.

Before the MOT run the vehicle for at least 20 miles to warm it thoroughly, them blast the warm engine to the governer in each gear, this dislodges any crap in the exhaust. Anything in the exhaust is blown out, this lowers your emissions readings as this soot is dislodged during high revving part of the test, this is then read as emissions.