Like in any game, there are cards that are just better than others. You won't know your opponent's decklist, but you can expect some cards common to an archetype.
For example, if I'm sitting across from someone playing Controlling the Message, I'll fully expect to see a few cards:
Daily Business Show
Commercial Banker's Group
Mumbad Virtual Tour
Enhanced AR Security
Hard Hitting News
There are also cards that almost always come paired. For example, if this CtM deck rezzes a Data Raven, I can be pretty sure they're running Quantum Predictive Model as well.
This knowledge comes with time, practice, and following the meta. The good news is, you don't need to know an overwhelming amount of cards, as you get better you'll gain a solid sense of which cards will be important to memorize, and which can just be bucketed into an archetype. For example, I never remember the specific numbers on Passport, I just remember that it's a mediocre breaker. If I need to know more, I can always read it when my opponent plays it.