Depends who you are playing. I usually just leave my tactic the same and when away, mould it to stop the home side from playing their game (I'm winning the championship at the moment and my away record is slightly better than my home).
Basically, look at their formation, players, listen to your scout report as to how they play and their main players. For example, if you're away at a team who play direct, with two "tanks" upfront who have got pace of about 3 between them, play high up the pitch and offsides.
Look at "opposition instructions" as well. I only use it for one or two of their main players - if they've got a pacey winger, I'll have closing down often, not tight marking and hard tackling. A creative midfieler I'll have tight marking, closing down often and hard tackling.
It could also be worth going a bit more defensive and looking at their defence. If they've got quick but weak defenders play a target man and hit him. If they're strong but slow, play deep, counter attack, have a quick player upfront, set him as your target man and have "target man supply" set to run onto ball.
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