Hmm...I aim for as close to my ideal look as I can manage, I suppose. That ideal would be definitively male.
I want a fit, toned body that's neither scrawny and lanky nor bulky or...too muscled I suppose. I want the mesomorph male body type, again without necessarily being bulky. I want hair in the right places: good scruff when I want it (i.e. I don't shave), a happy trail, hair on the arms and hands and legs and feet (well, more hair), hair on the chest even so long as I don't have a hairy back. I want a more defined face and jaw. Bigger hands and feet wouldn't hurt either. And, of course, the appropriate equipment -- preferably a bit larger than average, but hey, we're going with ideal, right?
I'm already around 5'7" -- I'm between 5'5"-5'6". I'm fine with my height as is, but that's not to say I wouldn't complain about a couple more inches...in height, that is. I want more than just a couple elsewhere...
Personality-wise I like a confident girl, one I'm still comfortable talking to and who I feel is hearing me and truly listening, one that pushes me a bit but doesn't nag. I like a girl that will call me on things, challenge me a bit (God is that hot), hold conversations from the silly to the serious. I like a girl that's straight with me, one that doesn't feel the need to try and change me or anything, one that can be naughty and a bit of a tease even (both in a naughty sense and otherwise). I like a girl with a sense of humor that can take a joke and sarcasm and can dish it too, but who doesn't take things too far. I like a girl who's intelligent too. Sweetness doesn't hurt at all. I like a girl I can have fun with in all settings, and can look damn fine if appropriate when we go out -- better yet if she can look damn fine regardless of what she's wearing. Though I like to be able to take the reigns and whatnot, a girl who doesn't have issue with surprising me by doing so sometimes is nice, so long as I'm not made to feel I'm just along for the ride and have no real control. So, a girl who can take control (especially in bed -- or wherever we happen to be) but who isn't about control, who still involves me. Okay, I will admit, it's more of a turn on and more in my interest to be more in control, to take care of things more, or at the least share that equally, but not at all so much if she's running the show more.
Can't forget open-minded as well (reason I edited this). Not only due to the whole trans-thing, but also...well, I'm into a lot of things, shall we say. I'm a hugely open-minded person and have no issue seeing both sides in matters even. Someone who is narrow-minded wouldn't work well in just about all aspects of my life.
A feminine girl isn't necessarily a huge thing. Actually, I like a girl who likes to get dirty at times (or at least doesn't mind), and can hold her own with "the boys" -- but I like her to have a femininity to her too. I think that kind of combination is insanely hot. Naturally, that lends to high-maintenance not being my thing -- I'd disappoint there as I'm not inclined to entertain and indulge that.
As to what turns me on immediately...haha, well, confidence is definitely one of those things. I've learned that suggestion immediately distracts me and catches my attention regardless of what I'm doing: whether the suggestion is verbal or physical or both, and whether subtle or vulgar and obscene. A cute, kind of flirty girl is a turn-on for sure. I'm sure there's more...but those are the most immediate turn-ons.