yeah more details and description of what seems wrong will help. preamp filters can help and i find using a preamp filter and then doing a background noise denoising type processing can help you pinpoint the signal of the instrument you want if you dont have a sound proof area and want a little more control over that. also like what kind of mastering effect are you using, what is it you dont like about it, what setup are you using to listen back to it, all stuff that could help people respond here (or if youre really looking for experienced responses you could ask on an audio website forum and i bet a ton of people would be happy to give their thoughts and advice)