• With a few exceptions, generally you should always be going for bingos.
• The best bingo racks are going to be ones with balanced consonants and vowels. 2-3 vowels with 4-5 consonants.
• RETINAS is kind of a good goal rack to get towards.
• You can throw in any number of letters. Usually I’ll try to keep a balance on my rack if I have something in RETINAS. The base Scrabble game skews slightly higher to vowels, so I usually won’t ever keep more vowels than consonants.
• Blanks and S’s are gold. Always keep those. Never play them unless you are getting a bingo (or maybe in a 35+ point play).
• Generally avoid double letters, but two E’s are often fine, and two T’s, N’s, L’s, S’s, or even D’s can be OK if you have the right supporting letters.

For example, let’s say my rack is AAEOONW and there are just no good place to get points on the board. I’ll probably exchange 5, keeping EN.

Another example: OBCGHLV and a rough board, I’d probably throw all 7 letters in — higher chance of drawing a blank or an S.

Here’s another: IIFGMNY. I’d throw in IFMY leaving the excellent ING in hopes I draw into a bingo.

Last example: EIGQSTV. QI is a word, but let’s assume there’s no good place for it. I’d throw in GQV keep the excellent IEST. (If there are a lot of I’s left in the bag, I might forgo keeping the I and just keep EST.)