The idea is fairly simple: fake words can get big scores easily, but you can't rely on the AI to not challenge you. So get another human player that refuses to challenge you. The best plays generally involve three Triple Word Scores on a single word, plus high-value tiles in the "main word" and in particular on the Double Letter Score tiles: one can easily exceed 2,000 points twice per game like this. (And as each translates to a point for the game's rank system... you get the gist.)

Probably can be optimized further, especially as I only found out ideas on the fly, screwed my own setups up, was sometimes distracted, and - only as I'm writing this now - not properly taking advantage of at least a double Triple Word Score after the main two ones are claimed.