How do you prep substrate X?

Because of the fact that there is more than one category of substrate, it is very hard to provide one answer. Depending on which substrate you are using, a good place to go for advise is https://www.3m.co.uk/3M/en_GB/bonding-and-assembly-uk/ failing that the specific TDS of the specific adhesive, which we can obtain for you if you do not have a copy.