To achieve a high score in Block Blast, focus on clearing multiple blocks in a single move by strategically placing pieces to create combos. Always plan ahead by analyzing the available space and future blocks, aiming to complete lines or clusters to maximize points. Clearing multiple lines or blocks at once triggers bonus points and power-ups, which can significantly boost your score. Keep the board as clear as possible to avoid running out of moves, and utilize special blocks effectively for high-scoring opportunities. Consistent practice and planning are key to mastering the game and reaching high scores!