Outracing your opponent means focusing more on acquiring cards that are easy to obtain/use (but tend to be weaker). End the game before the opponent's plans come to fruition. You'll likely still invest resources in early scaling, but you need to be able to switch gears before your opponent has time to outscale or outlast you.

Outscaling your opponent means focusing more on acquiring cards that are stronger (but tend to be harder to obtain/use). You must predict how "greedy" you can be with investing your resources in scaling effects before your opponent wins. You must plan to start cashing in on powerful card synergies/effects before your opponent closes out the game on their terms. Some games provide block/heal effects that slow down the enemy long enough to get your own engine rolling.