Hey Studio!
The piano could use a little sustain and reverb. The sound of the piano just needs to be a lot softer than it is right now. Maybe even reducing the velocity of some of the louder notes.
The muted electric guitar either needs to be louder and crisper or not there at all. It’s too quiet, and kind of detracts from the piano melody at the moment. If you have a real guitar I’d suggest using that if you know how to play it.
As to the strings, I’m not really sure how to improve the sound other than some EQ and Reverb. What VST are you using for the strings? Strings that are as upfront in the mix as yours is need to be super clean, something that really isn’t possible without a good VST.
Cheers!