The simplest method is to always bet on the team that’s less popular. The spreads the bookies set aren’t a reflection of the probabilities (at least not directly); they’re a reflection of how they believe people will bet, and the more popular team will have people betting on what they want to happen, not what they think actually will happen.
Of course, the downside of this is that if you’re betting against teams that your friends like, it might make you unpopular.
I once ran a pool with over 100 players. I’d throw in some “robot” teams on the standings spreadsheet just for fun - things like “all favorites” or “all home teams.”
One year one of the robot teams won the yearly pool by about 10 games over the best human player. That team was “first alphabetically by city name.”
When you’re in a pick against the spread pool it’s > 99% random. I wouldn’t worry about it too much.
I played a football pool once that included college and pro games. I sucked, usually missing far more than I got. One week I played two sheets. On the first I really tried hard to do well, while on the second I just reversed the picks from the first sheet.
My reverse choice sheet won! When I told the guy who managed the pool that was how I won he got really pissed off at me.