If you didn’t already knew, IK Multimedia’s infamous guitar modeling VST “Amplitube” is now free. Of course there are about five or so different versions and the free version is only the most basic version. But here are a few presets that can help beef up your guitar sound. Most of these are modeled after a specific artist/sound, but can be a good start for your own sound.
P.S. You will need a program that can open a .rar to use these, I would suggest 7zip.