There is a set of two Triple Letter (TL) bonus tiles next to each other, with a space in between them, at the middle of each edge of the board. There are also four TL tiles in the middle of the board, spaced in a square, each five squares apart. I recommend going for it at the beginning of the game, with a secondary profile.
Use your main account to send your secondary profile a game. Play a word across the middle. Then, with your secondary account, get them to play a word vertically either above or below the starting word, then switch user back to your main account. You can now go across two of the TL tiles either above the starting word, or below the starting word. If you don't have a good enough word, just play off of one of the end letters of the starting word, or exchange your tiles. Switch to your secondary account, exchange tiles or pass, and then switch back to your main account, and try and get a word again. If you truly are stuck for a word, I suggest using the anagrammer located at http://margana.ghacademy.org/
Remember, please don't use the above anagrammer against random people, that's not fair!