I don't have much data or calculations to back this up, but if I were you, I would

1. Decide how many options I want to exercise
2. Exercise the oldest options until I have exercised as many as I decided in step 1 (probably rounding up or down to the nearest whole lot)
3. Sell the shares with the highest cost basis. This is for two reasons. One, to minimize the income taxes this year (and defer as much income tax as possible). Two, because there are some negative (or at least non-intuitive) tax effects when you have non-qualified stock option exercises that sell for a price lower than the strike price.

I don't have much data or calculations to back this up, but if I were you, I would

1. Decide how much (dollars or shares) I want to exercise
2. Exercise the oldest options until I have exercised as many as I decided in step 1 (probably rounding up or down to the nearest whole lot if it's anywhere close, just for simplicity)

If you just want to exercise to and sell, go ahead and sell all the shares.

If you want to sell some but not all of the shares: 3. Sell the shares with the highest cost basis. This is for two reasons. One, to minimize the income taxes this year (and defer as much income tax as possible). Two, because there are some negative (or at least non-intuitive) tax effects when you have non-qualified stock option exercises that sell for a price lower than the strike price.