It’s much harder to sort out a sound thats not cutting at the mix stage than to get it right at the source at the very start of the track writing process. It might sound really obvious, but it’s such an important guideline when creating any sound, especially with a bassline:
Get the sound right at the start!!!
Don’t make life even harder for yourself by using bad quality sounds and then try and fix them up. Stop and listen to what you’ve got. Don’t be afraid to get the Spectrum Analyzer and meters out to see what’s happening, get it right in you synth or sampler first.