Welcome to the forums! Glad you've decided to join us in deckbuilding.
So...to answer your question, there's a lot that can be done with this deck. First question to answer is this:
1. Am I wanting to be competitive or casual?
See, Derevi has this weird quality of being able to be aggro, control, and combo all sort of twisted into one--at least, on the competitive side of things. If competitive is what you want (which, while not something I particularly enjoy, is something I can make tons of suggestions for), we can make that.
Glare of Subdual,
Opposition,
Edric, and whole host of other cards make Derevi into
a general who is banned in French commander.
If that's not the case, there's still a lot of work to do. Unfortunately, we first need to find you a direction and then also talk about strategy.
You've mentioned this having been bird/wizard subtheme, but obviously you found it unsatisfactory. Either due to that or even with the subtheme, this deck is fairly dysfunctional. You have an awkward combination of big creatures with
possibly relevant abilities and small creatures which get bent over in a stiff breeze (although, there actually isn't a whole lot of them; your average converted mana cost for creatures is likely somewhere around 4.5, and that's nowhere close to small creatures).
The best thing I can advise at this point is to pick what you really want the deck to do: commit to it being entirely birds and wizards; commit to the Inspired ability; commit only using cards costing equal to or less than $1.00--whatever it is, figure it out first. Theme is very important to helping cut out cards you don't need and replacing them with cards suited for the power level and thematic elements you are hoping to achieve with the deck. For instance, see this
9-Rare Derevi deck I play (well, it hasn't been updated in a little while, but I should really consider looking at Khans cards which can go in).
If all you are really looking for are 'good stuff' cards to put into the deck, then that's possible; however, I have this feeling you'll find that deck lackluster.
. But as I was saying, following your suggestions, I have made a list of some cards I think might do well in this deck. I also have made a list of some cards currently in the deck that have 5 seconds to tell me why they deserve a slot.