There are a lot of ways to make it sound better. EQ is your most important tool. With EQ you get rid of the frequencies that you don’t want, you make room for each instrument so that it sits well all together, you also boost frequencies that sound good for each instrument. Then you have a compressor which will make things thigher and it will give more energy but you must not over do it because you use compression only when it’s needed. There is no reason to compress distorted guitars because they are already compressed. What you can do it parallel compression on drums. Parallel compression is making a copy of a signal and then brutally compressing it, making it sound like shit and then you just mix that in with the original signal and it will sound waaaay better. So you have the original drum signal and you have a copy of that which is brutally compressed and you just mix it in with the original and that’s it.