Considering you have limited time to practice, my first recommendation would be to stick to decks you're already comfortable on. Obviously if you have a 20% matchup against a common deck in the meta then you are going to need to include some appropriate tech to improve your odds, but try not to stray too far from your comfort zone.
I won a regional at the height of the IG Asset Spam/Slums Whizzard meta during Mumbad Cycle playing Apocalypse Maxx and Temple NEH because those were the decks I knew inside and out, even though Whizzard and IG were far and away considered the decks to beat. I'm probably an above average player at best, but luck was on my side and I was playing decks that I had played for literally months leading up to the event.
On the other hand, I've also shown up to Regional and higher level tournaments with card-for-card netdecks of the "undefeated winner of X regional" and fallen flat on my face due to inexperience or just clash of playstyle.
When you have to grind out 12+ games of Netrunner back to back (assuming you don't have the luxury of ID'ing most games), it really helps to be on something you can play like the back of your hand, even if it isn't objectively the best deck out there. Sometimes by playing something a bit outside of the metagame you can also throw off your opponent's ability to predict your actions which can also come up big in the swiss rounds.