Once you have recorded a large amount of material intended to be used as sound effects, the next step in creating a sound effect library is to edit this raw audio. You will need an audio editing software that will allow you to cut, fade in/out, normalize, and eq your tracks. There are many professional digital audio workstations (DAWs) out there for purchase and also several useful freewares easily found on the internet.
First import all of your raw .wav recordings into the software of your choice. Try to import 40 or so for efficiency, though you may attack one at a time, and solo each track for editing which mutes all tracks except the one with which you are working. Now you are ready to edit your sounds and then bounce them into completed sound effects. The following points will assist the quality and efficiency of your work.
1. Use normalization on each recorded sample first. Normalization increases the amplitude of each .wav file, in other works amps the volume as loud as can be.
2. Secondly, some frequencies may affect the quality of your sound effect and you should use eq to eradicate these sonic culprits. A great sounding bird chirp, for example, may be compromised by an offending air conditioner. But, by cutting all frequencies below 2,000 Hz you can get rid of the AC and keep the lovely bird sound.
3. After cleaning and amping the audio next find a clean break with which to start each particular sound effect and make a fade out or let the natural reverb of the sound fade out by itself for 1-2 seconds.
4. Create a stereo 48k 24bit .wav file of your recording for video editing purposes. This quality of file is highly valued by individuals and libraries that license sound effects and will earn good money.
5. Make as many versions of each sound recording as possible to increase your number of products. For example, if you have a dog barking 20 times then create sound effects with one bark, three barks, six barks, 10 barks etc. switching up the combinations of barks. This could easily give you 50 or more sound effects from just that one sequence of dog barks.
6. Use pitch shift and other effects to create new versions of each sound to increase your number of products. For example, a burp sound effect could be pitch shifted down to create a monster burp sound and pitch shifted up to create a more childlike sounding burp.
A little knowledge of the ins and outs of audio editing combined with the above tips will allow you to easily create professional sounding effects that can be licensed time and time again by multi-media editors and producers.