My first song - suggestions encouraged

Hey. I really liked this. For the first 50 seconds it was quite beautiful. You go out of key in a couple places but that's not the worst crime in the world when it's this style. Lyrics are very cliché but that's to be expected with a love song and I don't have a problem with cheesy cliché lyrics. They work. At first it reminded me of the Lyndsay Diaries. Are you a Dallas Green fan?
As for other instruments, I think you would benefit from a second guitar.

Hey. To be honest I thought it was a cheap guitar haha. It sounded fine though. I think you hold notes too much as well. Perhaps work on that? Check out Dallas Green. He goes under the name City And Colour. Fantastic musician.

I'd go the whole hog, and add a guitar, a bass, and some drums.

For a nice musical break, I'd also add either a brass instrument or keyboards.

But then, I like the bigger bands, and aren't really one for solo artists.

If you do add drums, keep them quiet on the equaliser or whatever it is that controls all the different sound levels. Your voice is a really nice one, but it doesn't want drums overpowering it.

Think jazz drums, but a touch quieter perhaps.

In fact, the only instrument I'd keep at the same level as your voice is the bass, and play it slowly.

At least, that's what I'd do. Hope this helps.