When you begin working on your film project in Adobe Premiere, Final Cut or any other piece of software the first thing you’re going to do is import your assets. In so far as sound is concerned you’re going to import your dialog, sound FX and music tracks.
How exactly you do this is up to you but most people will bring in their dialogue first and place each character’s dialogue on a different line. If you have the ability to color code the tracks in your software please feel free to do so as it can help with organization.
After bringing in and editing your dialogue tracks, on a different track you can bring in your atmosphere / room tone and sound effects. Again, keep these separate from your dialogue.
Finally bring in your music. Music will also often begin and end not just inside of a scene but before and after a scene so keep that in mind when editing. As in, don’t hack off your music in a scene before the end of the scene if you know it will continue beyond a sequence.
Also keep in mind of the capabilities of your video editing program. You can also import a combination of these things and begin working from there while utilizing the ability to solo or mute tracks individually.
By the way, I wouldn’t make the beginner mistake of editing everything on the same track. Once you learn how to really edit dialogue, you’ll know that just like video the takes that you’re listening to may not have come from that angle and dialogue often overlaps and switches perspective when it may see most natural. As in, you’ll hear the other person speaking prior to us seeing them and something like that is really hard to edit when everything is on the same track.