1. If you aren't already, be sure to use headphones or earbuds so you can really hear the tiny changes in the audio. Keep in mind that the speakers on these computers are crap.
2. Control audio levels in Premiere Elements by moving the yellow line on the audio track up and down, not with the mixer window. This is because the mixer creates realtime changes within the clip with keyframes, and will not affect the entire thing.
3. If you need to, you can change the volume of a specific part of a clip (For example, if the interviewer spoke loudly and the interviewee spoke too quietly) using keyframes, as mentioned before. This method is better than cutting the clips and changing the volume, because then you get a sudden jump in levels. Select the clip and set the cursor where you want the gradual volume increase to start, and hit the keyframe button to the left of the clip. Then move the cursor forward to where you want the clip to be at its new volume, and add another keyframe. Then do the same where you want the volume change to end, then drag the yellow volume bar in that particular area to where you want it to be. It should look something like ^this^ when you're done. This is also the preferred method to fading audio in and out of segments, because you have a lot more control over the final product.
4. Use the audio transitions "Constant Power" or "Constant Gain" to fade the audio between two clips. This creates a more polished, professional sound (We all know what it sounds like when two clips are simply placed back to back with no transition, you can tell just by listening where one clip ends and the other one begins). If it doesn't let you place a transition between the two clips, it's probably because there are no "handles", which means you are trying to fade audio that isn't there because it's either the very beginning or very end of the clip. Trim a little off the beginning or end of the clips you're trying to fade, then apply the transition. Just be sure that your handles don't contain any unwanted audio, like the cameraperson saying "Go" or "Okay we're good" or something like that, because you'll hear it within the fade.*
5. When finished editing, play back the project and watch the audio levels moving up and down. Make sure that the volume of each clip (Including music and sound effects) stays in the same general threshold on the audio meter. Also use your ears and common sense to make sure it sounds good.
6. When you think you have your volume levels where they need to be, play the project back and listen to it, just to be sure that everything sounds the way it should. You should be able to clearly hear what people are saying, music and sound effects shouldn't be too loud, etc.
7. Finally, click: File > Export > Export Audio and save the file to this episode's folder (Save it as something distinguishable, not "swaws.avi" or something like that). Open the clip in Audacity, select the entire thing…