I presume you're mainly referring to Paper 1, as you should have enough time in Paper 2.
1. Plan your time before the exam: reading time, planning time, modelling time, writing time, spare time.
2. Plan your model during the reading time. Knowing what you're going to build before you start will help avoid reworking anything, which is a sure way to run out of time.
3. Try get to everything, even if it's not at a great quality. Do some data checks, move on, do the model, move on, do the audit trail, and then go back and improve things. Like adding formatting, and more data checks, and better labels in the model, and more detail in the audit trail.
Oh, and the obvious one:
0. Learn to type faster. A speed of 40wpm is easy to achieve with 2-3 weeks focus, and will significantly improve your output.