Start with Broad-Coverage Words: Since you are tackling 4 words at once, use words with many vowels and common letters. Words such as CRANE, SLATE or AUDIO work to eliminate a great deal of potential characters right off the bat.
Track Each Board Individually: Work on each grid one at a time. Note the track of which clues relate to which grid. Using marks (either on paper or in your head) can be very effective in ensuring correctness.
Test New Letters Quickly: During initial guesses, try new letters-the first 3 to 4 should really be used on new symbols. The more alphabet alternatives you examine early the higher your chance.
Make Use of Word Structure and Frequency: Typical letters exist that show up more often. For instance E, A, R, O, T, L, S in most words. If you have managed to uncover few letters then look at structures that words may follow.
Watch for Double Letters: Not only you will find double letter, like LL, EE, SS but sometimes the same letter could be in other puzzles.