Thread mastering?

To ask "What goes into mastering a track" gives the hint that you may need to backup. This is my opinion and others may agree, but mastering isn't a requirement for getting a great sounding finished product. If your tracks dont already sound great then you need to go over every track again and work on that. It's difficult to answer this post because of the lack of information and I have no idea what you have done. In most cases listening to a posted mp3 is a good indication of a person's capabilities.

for instance, when i mix from one of my songs to a regular song, i can tell the difference in sound and they never blend right.. here's a remix i did a few months ago, listen to it and let me know what is need to make it sound more.....fuller???

http://download.yousendit.com/059E232E7F0EC2B3

Joey, unfortunately I wasn't able to hear you MP3 because of that site. But from what you say there may be a few suggestions which can help "meld" your music to sound more cohesive as a mix.
First, how are you panning your various tracks? Seperating parts provides sonic "room" for competing frequencies and gives a more spacial feel to music.
Are you eq'ing your individual tracks to get the sound you're seeking? You mentioned that your songs are "too crisp or clear" which may not be a problem at all depending on the style of musis or sound you are trying to achieve.
Lastly, are you doing any overall final mix compression. I often recorded individual tracks which sounded great by themselves, but just so-so in the mix. But after a mild application of compression ( 1.5 - 1.7 ratio) many times they settle down and blend much better. Hope this helps some.

%1$s a écrit mastering isn't a requirement for getting a great sounding finished product.

You obviously never heard a good mastering session being done.

Without mastering you might have a good mix, but that's as far as its going to go. Your song is mixed on a specific system and what happens is that you put your song on cd, listen to it somewhere else (in your car, or at your friend's home) and think "damn, it sounds great in studio, but it sucks here! why??!".
THAT is why you need mastering.

And its not a "go-by-ear" thing that you can do at home, like recording or mixing.
You need professional tools, a dedicated room and specific knowledge to get some results. It's not just about the volume!
long story short: get the job done by a mastering studio.

listen to some demos from this mastering studio to understand what i mean:
http://www.xarcmastering.com/demos/

maybe i didn't explain myself well...
25 years ago times were different, mentality was different and those cassettes were considered the recording standard. people got rich then, but now they would be ignored. its pointless to put the old times on the same level of modern times, because they are totally different.
Today standards are much higher, and a good commercial quality for recordings is achieved through mastering. There is no arguing about that.
so:
YES, mastering is required for a great sounding product.
NO, mastering in not mandatory.

..but in case you are thinking of a home-made mastering, good luck.

I just recently went through the mastering process with a professional mastering house for the first time with one of my own bands. I will never go without doing it again. The most important part about the mastering process is that its someone else doing it. Someone who's been uninvolved with the bulk of performing and recording/producing the project. The second most important part is that its done by someone who has professional equipment and a good room and KNOWS his/her room and equipment well. Any professional in the industry will tell you theres no magic pair of speakers or room or placement that gets the job done, its the relationship of the engineer to his room and equipment.

If you're burnin CDR's and making your own cover art, you may not be ready for this step yet, but if you're spending $1000 to press a CD, you're making a mistake if you dont go through the mastering process. It will tack maybe an extra 50% onto your costs, but the difference in quality and confidence you have will be immeasureable. I also recommend someone who was at the original sessions (either the artist or the engineer/producer, whoever, someone who can say why you did X) attend the mastering session. It'll make it take a little longer, but you'll learn alot.

I can't say it enough: If you're trying to be professional at all, do not skip mastering. Do not try to master your own stuff. It's not worth the money you'll save.