Action selection in a hidden movement game that may require more information to be complete
Most games that let you select a variable number of something in secret, will either give you small tokens that you hold in your hand, or by giving you a screen to hide items behind. Some also give you duds that you can place instead of something useful, to bluff about what you're doing.

For example, Shogun lets each player pick an action for each province they have. Each action can only be picked once. What they do is give the player a card for each province they own, and they put their province face-down below the icon for the desired action. 

When you want to expand this mechanic so that you can select additional options, you could for example slide additional cards under that action, then give each player a few blank cards that they can use to bluff about where they are taking serious actions.

Alternatively, if the players take one action at a time, it's easy enough to just give them a screen. They put all the stuff that is used in the action on one side, and everything else on the other. That lets them completely hide what they are doing from everyone.

Some games also do the same thing, except they use a bag. This works really well with tokens; you put all the tokens you want to use in the bag and the rest you keep behind your screen. Or you can use a dial for selecting amounts (used by many games).