The complete process of bringing song from a ruff idea to a finished master is detailed and involved.
Often artist and songwriters don't have a good grasp of this process and hope for that magic one step to give their song "that sound".
Fact is to get "that sound" you need to take many steps and pay attention to detail at every step, don't skip over anything, it will only add more pressure later down the track.
Having said that, here is a brief guide to what it takes to bring a well written song from something that sounds good in you bedroom to a finished master.
1. Arrangement - once the song is well written it also needs to be well arranged. Many people arrange as they go. Thats fine and arrangements will change during the recording process as you hear your song played back, but spend some time arranging your song well at the outset. A song that lifts in the chorus's not because you smash the faders but because the arrangement it self lifts and thickens makes the mix process easy and gives a song a much more organic sound rather than something processed to get the same feel.
2. Set up - Setting up for a session is important. Its your chance to hear the song live and start making decisions like instrument selection. What type of snare is going to fit the song? What type of room is going to work? Do you want a dead, close mic'd guitar or a bigger open room sound? Start imagining the song in your head and make some good choices. This does take some experience as you have to see a little into the future at this stage. A good tracking engineer will be doing this as he sets up.
3. Tracking - tracking is your first stop to hear what your song sounds like. Its the stage where you can actually start to mix as well. Im a big supporter of mixing in the tracking process, you mix with microphone choices, pre amp selection and analogue gear. Remember when you record its that stage when you are in the analogue realm so its a great time to tastefully and carefully use what you have in terms of out board gear to take a step in the right direction mix wise before it gets converted. Use it while you are there and don't wait till later when you can make clear decisions right there to move in a certain direction.
3. Mixing - most people put a lot of weight on the mix process and it is one of the most important steps. But getting the other steps around it right and mixing a little as you track takes the pressure of this stage as you already are headed in a direction, now you just head a little further down the road in detail.
4. Listening - after mixing, take some time off, come back and listen to your song. Is it what you wanted? Does it need something else? Does something need to go? Don't be afraid to re-record or add some additional parts at this stage. You now have your music in front of you, no more guess work so fit the final pieces of the puzzle into place and don't be scared to change. Ive seen a lot of people not willing to change as they had an idea in there head at the beginning and got too attached to it. If its not working now you hear it in front of you, simply change it. Sentimentality does not compete with reality.
5. Mastering - assuming you have a good mastering engineer this the final gloss on your music and if you have taken care at all the steps then you should have something that will be easy to work with and just polish whats already shinning, not major surgery.