Bet the number, not the team. That has long been a motto for sharp bettors. You create a model of one form or another, you decide you'll bet on a given team if their number is, say, -9 or better, and you wait to pounce. You don't just say "I really like how Team A has looked lately," or "Team B is due a good result," or "Team C always loses big games on the road." Creating a model or set of heuristics for yourself and having a general understanding of the distribution of probabilities will probably take you a lot further down the road in the betting world. It's not so much "Bet the number, not the team," as it is, "Bet the number and the team," but that doesn't sound quite as good.
Using publicly available ratings and models can help, too. My SP+ ratings, for instance, generally grade out over 50% against the spread on all FBS vs. FBS games. I post weekly projections on Twitter and track them publicly. Projecting all games, with no adjustments for injuries, suspensions or other breaking news, SP+ tends to get the best of the books, however slightly.
• In 2018, it was 52.8% against the midweek spread, 51.2% against the Caesars closing line.
• In 2019, it was 53.4% midweek and 53.2% against the closing line.
• In 2020, it was only 51.2% midweek but 52.8% against the closing line.
• Early in 2021, despite some early misfortune on really tight lines -- it's 11-16-1 (41%) in games in which SP+ and the spread disagree by less than a point, which should even out over time -- it's back at 52.8% against the midweek spread and 53.4% against the close.