When your enemy looks at your forms, s/he will have to keep very strict track of what form is where as there is some chance a mistake will be made as to which form is which.
The Woodens cloaking ability makes it a prime candidate for this tactic & moving in and out of Forest regions only furthers the confusion as they attempt to keep track of what Wooden is where, or even how many of them there are!

As for the cloaked forms, it serves well for surprise attacks.
If you summon one form then move it and cloak it and summon a second, your foe is likely to believe that you've still only the one form and simply have not moved it. (I would even go a step further & order the 2nd for 1 less fuel than the 1st so it really looks like it hasn't moved)

Be sneaky, hide your temple as it appears & then Hide the form as you summon it, even this may lead players to believe you have yet to summon a form if they're not paying a lot of attention to your resources.

As the game progresses, you may find yourself with access to several form types so don't be afraid to stack a few together & experiment with form combinations as touched on in the hulk & colossa mails.

Lastly & again...
*Arrange temple swaps in your initial Nap dealings to give yourself several choices.
*While not always possible, try to keep troops with forms so fury can be gained from these fights.
*Make the best use of your forms special abilities.
*consider the terrain &/or temple swap arrangements when choosing a religion.