Hi this site is all about how to master the art of audio mastering. This can be a difficult task and is often best left to a professional mastering studio. With some practise and tips from this site however you can at least create a pre master that will be suitable for sending off to a mastering house.
One thing many amature producers make the mistake of is running too many processors on their master buss while mixing. This is usually done in an attempt to recreate the sound they hear on radio productions. The problem with this is that radio transmissions normally have an extra stage of compression and limiting applied for broadcasting which artificially inflates the volume and ‘impact’ of the song. Using a commercial bought cd or mp3 is usually better as a reference as at least this will be pre radio processing.
It is ok to use some mastering types of processing on the mixm the trick is to not overdo it. If too much processing is applied this will then influence mixing decisions and can lead to what is essentially an unbalanced mix ‘fixed’ with the mastering chain processing. If at some point these processors are turned off, say for sending to a mastering house, the mix can fall apart and sound very unbalanced. This is a lose-lose situation as the mix is not suitable for mastering in it’s processed state yet at the same time also broken when taken off. The only solution generally is to redo the mixdown with safer more conservative settings on the stereo buss.
The choise of plugins and make a big difference in the final sound of a mix and master but the skill of the mixer/mastering person is more important. Also sound choises, arrangement, and other aspects of the song itself will play a large part in how the final mix sounds. One pitfall is to choose sounds that don’t mix well together initially in the hopes that they can be fixed in the mix during mixdown. This is a mistake as even with judicious use of eq and other mixdown effects it can be very diffucult or impossible to make sounds fit together in this manner.
A good idea is to actually do some premixing as you go so that a clear picture of the final mixdown can be heard early on. This allows the engineer to forsee any issues with the choise of sounds or arrangement before they are commited thus saving the problem of trying to make them work solely with mixing skills.