Here are some hardware modification to improve your Baofeng’s radio performance. These are not my own but an article found on the internet from DG2IAQ and KX3DX. If you’re into fixing and breaking things then this article is a must try. I have done some modification on my radio and I can say that the performance enhancement is worth the trouble. See the preamp modification using Vox transistor here.
Another modification lists from KX3DX for UV5R.