Here are some tips you can follow before sending your project to a mastering facility. Although the items discussed here doesn't cover all scenarios, following these tips will ensure that you get off to a good start, get the absolute best results from your (hopefully reputable) mastering facility and then of course it will ensure that your mastering engineer well, just simply loves you.
You should obviously check with your mastering engineer (ME) on acceptable formats but in most cases you will be told that to always keep your files in the highest possible resolution in either WAV or AIFF format. Quite frankly, if your ME tells you to send an audio CD as your master, leave that mastering facility faster than you can say oops!
If you recorded your project at 24-bit, 96 kHz, for instance, render your mix to that same resolution without applying any dithering. Don't render your files to 16-bit, 44,1 kHz simply because it's going to end up in that format (Red Book). 24-Bit files leave more headroom for the mastering process. Dithering should always be left to the absolute last process which is usually your ME's responsibility. Most reasonable audio editing software packages will give you the option to dither or not when you render (export) your mixes to files. This might sound stupid (I wouldn't say it if it's never happened) but never render or export your files to a higher resolution than what it was recorded at, that will just worsen the quality.
Do not trim the beginning and ending of your files, leave everything intact, most ME's have the experience and 'feel' to help you make your album 'flow' and might often suggest different fade positions, lengths, etc. Another reason for this is that if you need noise removed from the recording, a good 'clean' sample of the noise is always welcome. If you have very specific ideas or requirements on how you want your master to come out, you might want to send a very good set of notes with the files to explain where you want your songs to start, end, fade, etc. Sometimes it might even be a good idea to send a reference CD of your fades, etc. with the job.
Don't write your files to CD using the highest burning speed available to you, even while this tempting because it saves time. Up to around 8x speed is quite trusty in most cases but 2x is preferred. If your CD/DVD burning software has the option to 'verify written data', use it. Nero Burning ROM for instance has this option. There is nothing more frustrating than sending your CD half way around the world only to find that some data on it contains errors or are inaccessible. If you're not sure how to check your CD, try copying the CD contents back to your own system, open the files and make sure they are what you expect them to be.
I know we are all tempted to compress our stereo mixes so they sound really tight and punchy. While that approach to mixing is perfectly normal, we are all guilty of over-compressing a mix at least once in our lives, yes me too. Over-compression causes a whole bunch of problems in a mastering facility however.
First of all, compression is one of those things which, once in a mix, can not be removed or fixed satisfactorily. I experience compression as the biggest problem with mixes sent to me. Sometimes I receive mixes (which are totally over-compressed by the way) with a note from the sender: "Please make it sound loud, but not over-compressed". This just reemphasizes to me that many audio engineers don't know how to use compression or limiting, especially on the stereo mix and, coupled with the 'mix to master' syndrome happening in many studios today, that can only mean one thing, more 'bad' mixes are hitting the road than ever before.
So what can be done about this? You need your demos to sound great, right? You also need to get rid of the transients and spikes in your mixes, right? Well, the answer is quite simple really, in fact many professional studios follow this method. Render two mixes, one with your compression and limiting and, one without (did I not tell you it was simple?). The mix without not only becomes the copy to send to your mastering facility (if you plan on doing mastering), but also an important 'unaffected' back-up copy of your mix. If you later find your mix sounds too compressed you can always reload the unaffected version and try different compression and limiting settings for your song.
Your ME should be experienced enough to know exactly how much compression and/or limiting is needed to preserve the dynamics for your particular genre of music. The ME will also know how much room to leave to compensate for the 'ugly' compression done by radio stations in general.
Another one of the worst things that can be done to a mix is the incorrect use of stereo enhancement effects on the overall mix. Stereo enhancers, when used wrong, will make your mix sound sloppy and un-tight. It can also cause phasing problems when used on individual tracks or the overall mix and this just opens up another can of worms. The rule of thumb for this problem is, never use stereo enhancers on a mix heading for mastering.
When a ME listens to the overall flow of your album from start to finish, he will know where and where not to enhance the stereo image of each song. In some cases the ME might even narrow the mix to better fit into the overall project.
Although CD-Text is not strictly Red Book format, this feature has become quite popular since the arrival of CD players that can display this information a number of years ago.
If you want to include CD-Text, always ensure that you send a printed copy with the names of the songs, the artist for each song (if different from song to song) and the album title. All these should be checked for typos like capitalization, spelling and grammar. If you have a weird way of spelling certain words like using 'da' instead of 'the' for instance, make a note of that to the ME. His natural instinct might want him to fix your typos, unless you tell him not to of course.
Now go out and have fun creating!