Collect your files into a Production Folder for your show. In that folder you can store the Cue File (the .scs11 file) and all the sound files required for the show. You can do this easily in SCS in the Editor - see Collect Production Files.

Using sound editing software, delete silence or unwanted sound at the beginning and end of each sound file. By viewing the wave form and zooming in to the start, you should find it easy to delete everything right up to the instant the required sound starts.

Check the entire wave form for clipping. If you have recorded a sound file yourself and the wave form tries to exceed the level limits, you will typically see the wave form butted up against the upper and lower limits, and this implies that your recording has been clipped. Re-record your sound file at a lower recording level to ensure a clean unclipped recording. If you obtained a sound file from some other source you should still check for clipping. Many sound effects files available on the Internet contain clipping. Discard such files and find better ones.

If your software provides the facility, you may find it beneficial to maximize the level (GoldWave provides this facility under Effects / Volume / Maximize). Maximizing the level will not cause clipping, but if the sound file was recorded at a very low level you will not get a good quality sound, even with maximizing. Generally speaking, maximizing the level of the sound file provides you with the most flexibility as you do not have to pump up the level on the sound desk just to make a low-level sound file sufficiently loud.

You can set and leave the faders on the sound desk at a constant setting (eg 'unity' or '0') and set the required cue levels using the cue's 'Level' setting. However, keep a hand on the faders to provide a correct, live balance between actors' dialog and sound cues.

Where you have a cue that auto-starts then the level of the cue should be determined and set in relation to the cue currently playing.

When you are preparing sound cues, remember that what may sound wonderful thru your PC speakers may be less than satisfactory when heard thru the sound system at your theatre. (Sometimes the opposite is the case. A thunder sound effect can rumble around the theatre yet sound almost crackly on typical PC speakers.) Try out the sounds at the theatre as soon as possible, and also look at getting some good speakers to connect to your home PC if that is where you are preparing your cues.