A good mix/master starts with the recording. It's vital to get good tracking performances along with using high quality instruments, microphones, pre's, compressors, EQ's, etc. A good song (and recording) almost mixes itself. A recording tracked in a bedroom with low quality gear and an inexperienced engineer will rarely be saved or compete with the big albums, even if it's been mixed and mastered by a professional. I've been engineering in commercial studios for over 10 years yet a bulk of my work in recent times has been mixing recordings that were tracked in home studios. While I can achieve excellent results, it's just never as good as something that I produced/recorded myself (or somebody else) in a commercial studio. I'm not saying that you can't get decent results in a home studio environment and I'm certainly not saying that mixing and mastering isn't important, I just can't stress enough how much the recording stage affects the final result. It's like building a house. If the foundation is weak, it falls apart! Don't be too hard on yourself, you're comparing your stuff against recordings that are tracked, mixed and mastered in high quality studios by professionals. And with musicians who do it for a living!! Working with a producer from the pre-production stage is also a big advantage. Keep plugging away, you'll get there. Good luck!!!