So I haven't played in photoshop for close to eight years, finally got back in it today and I am stuck. I have a photo that does not look complete, but I can't figure out where else to go. Also, struggling with manes/tails, but I'm hoping that they'll start looking a bit better with practice...

https://i.imgur.com/35i3MbO.jpg

Any and all help will be greatly appreciated!

I think it looks amazing! I would maybe add something to fill some "empty" space? even if it was like a bird or bug or small wildlife animal or something?

looks great to me, like Lemo I think I would ad something to the right of the pretty horse, flower, butterfly, dog, etc :)

if that's your first in a while, you have a really good grasp on graphics. A few things I would comment on, more so than critique .... 

1. because you have the horse off to the side, it is not the central point. The eye is naturally draw to the clearest central image - which in this case is the Bush. You can make the horse the focal point (no matter where you position the horse) by blurring the BG a bit. There are several ways to do that ... play around with it a little (smudge tool/Gaussian blur) and you'll find the style that suits you best. 

2. Shading is also very helpful to makes images seem more realistic/mesh better. Once again there isn't a specific formula to do shading (unfortunately) you just have to play around with it, until you find what works for you. 

3. blurring/smudging a fur pattern on the horse, is also an effect a lot of people like. Again, it's pretty trial and error. It's easy to go way to heavy though. So if your not comfortable w/it natural is good too. 

4. editing the eyes can also make the horse pop. There are lots of guides on horse eyes on DA and multiple sites. 

Okay, so I have given it another look after staring at it for a good long while... I went through and body smudged (totally horrifying and am super worried its over the top) , added in an eagle which needed to have the beak, eye and feet repainted... hooves have been repainted, shadows added, and played a bit with the god rays.. also blurred out the bush in the back as suggested... Let me know if you guys think this is an improvement and what other things are typically looked for...

https://i.imgur.com/HDrhALU.jpg

I think it looks great. Smudging is kinda tricky. Some people really like it, and some don't. Do it to the point that you like it. The only think I would say, which again is personal preference... is that the white glow is a bit strong.  It is very good at helping define features, but can be a bit to much. 
I love the sun. I have never had good luck with sun rays.

i love it!!

Thank you everyone! I did just open it back up and go over those white outlines with a good blur and holy moly theres quite a difference, good amount of pop but not so jarring!

Looks amazing to me :D

I'm not really good at teaching how to do stuff on Photoshop.. but one thing I really like to do, is read tutorials on Deviantart, especially when it comes to painting mane and tails.  I have some days where I struggle alot on perfecting the perfect mane and tail, lots of patience.. if you get frustrated close the program, and come back with a clear mind.  That's always helped me.  I think the image looks awesome!  

Seems like the horse is too bright....the eagle color matches well 

Thank you for all your help guys, I think I was able to pinpoint it and will hopefully get that up in the auctions soon (: You're all wonderful !