These tips are a big summary. There are lots of exceptions.

1. Usually don't take tasks of low values if you have that card.
2. Usually don't communicate if you see no problems in achieving the task. Reserve communication for problems.
3. On the other hand, don’t try to keep your communication for later. If the game could be lost in one trick, usually communicate immediately.
4. Mentally calculate the tricks performed when choosing tasks. This is particularly helpful when there are multiple tasks of the same suit.
5. If you have 2+ rockets OR at 5 players, it may be a good idea to take a task of a suit that you do not have any cards of (or have just 1 of it), especially in later missions. If you got only 1 rocket, try to avoid it (higher chance other players get high cards on that color).
6. If you have rocket 3 and rocket 4, play rocket 3 first as a means of communicating your rockets. (commander always have the rocket 4)
7. Draining rockets by playing them first is usually not a good idea (except if you got at least 3).
8. Take the lowest task you don't hold first when picking tasks: it's easier for someone to gain a task which is higher than his higher card of the color, than to win a low task he is holding.
9. In variant specific missions, give more value to later calls. They got more information to make their choice.

About communications: As a general rule, always assume the communication means the minimum amount of cards (so communicate y3 is the lowest yellow card tells he got only two yellows, potentially yellow 3 and yellow 9), then wonder if that makes sense to tell it or not:

1. If yes, assume that until you get contradictory information (the first card discarded by that person is really important).
2. If no, and it’s in a color he holds a task, and winning it with it is difficult/impossible, that means he got a rocket, and wants to win the task of that color with it.
3. If no, and it’s highest on a color he holds no tasks, that seems to say he wants to win his other task(s) using that color.
4. If no, and it’s lowest while he holds a task of that color, that seems to say he got his own task.

For a detailed guide, go here: https://docs.google.com/document/d/1w4rU2aaTluTH91sfSKyxd0shhHKpnPCaZCTxkl4PHOQ/edit (skip to part c) if you already read this).