Reaper is a fantastic DAW. It's supported on many platforms, is versatile, highly customizable, and comparatively cheap. You can actually use it for free forever without any feature limitations if you want. The only downside is that you get a nag screen on startup, but that's it. A license is only $60. Then, you can grab free effects and instruments from places like
KVR Audio. Grab samples from anywhere, including any gear you might have already (even your phone. Modern mics are pretty decent). Plug all of that into various tracks and mess around and see what you can come up with.
Some less-conventional pieces of software may lend themselves better to noise and experimental sounds. For example,
AudioMulch can make some interesting textures. That's been used by electronic artists like Nine Inch Nails (mostly around The Fragile era, I think) and Four Tet.