Re: Beginner question on keys/scales + basslines
Here's the thing. The key and scales used aren't always related. Using one scale throughout the sound will end up being sort of bland.
The difference in the scales you named is simply shifting the root. Don't think so much like "I'm writing a song in the key of c sharp minor, so I have to stick with a c scale the whole tune. If you have your melodies shift around, it's usually nicer. You don't have to always resolve on a c sharp, and you can always throw in accidentals. Something I usually do is write three parts. The melody, the counter melody, and the bassline. The melody is usually the main focus, while the counter melody fills in the blanks and gives two levels, and the bass for me is usually a mix of the two with it's own groove every now and then. Don't let theory take complete control over your music. Use it to pick a key if needed, then do what sounds good. Theory outside of basic notation is more of an improvisational skill, and an analysis skill more than a composition skill. If you don't throw in accidentals outside of the key signature, your music will end up being pretty bland.