I am shocked to hear you produced such a great piece for your first attempt! Of course, every track can improve with fine tuning. Here is my advice for producing orchestral:
If you want to compose orchestral, I recommend buying the best out there - East West products, such as East West Symphonic Orchestra (the one I own and love). The strings sound great, but probably the best one would be Hollywood Strings (which I don't currently own).
Next, is to explore your sound library, and figure out what instruments will sound best in your piece of music. For example, if you choose to produce a romantic or sad piece of music, maybe a solo violin would suit the part for the main melody?
Get to know what instruments go where and how to place them so they fit in your song. Listen to a lot of orchestral and hear to how the music tells the story, at the same time keeping track of what instruments are playing at what time. For example, if you are listening to a soundtrack of a film, look at what is happening in the film and how the instruments interacts with the film. How does it correlate? Maybe you hear more horns at the point of victory, or lower octave strings and sharp staccatos at the point of horror?
A good technique is remembering to build crescendos before a change in your song. A good tip is to use woodwind and violin trills, harps, timpani and snare rolls, and also cymbals at the point of climax and transitions.
Using automation I say is a must (this is more advanced) for making it sound professional and realistic. You would want quiet and loud parts in your orchestral songs, because a real orchestra has dynamics and movement. This is where 'read and write' comes into play. I use a product called Leap Motion and software called Geco and loopMIDI on Windows, which helps me use my hands as a signal to change the volume, expression, panning, and other effects of the instruments during plackback. When 'write' is selected on an instrument, it records this in real-time, and 'read' just means to enable what you are recording so it is heard during playback. Of course, this is for advanced users, so I wouldn't want to confuse you at this precise moment in time. There are a good amount of tutorials on Youtube for these products.
I really hope I have been of some help. Please contact me if you would like more advice, and I will do my best to answer.