How do I make up a cool guitar riff or song?
Skip the music theory for now. (Although I do recommend getting familiar with the pentatonic scale eventually) I like Rie’s answer the best…play around with notes. Also, when you’re away from your guitar…hum little melodies in your head, or try to hum guitar riffs…you’d be surprised what you can come up with. The problem is…transferring your thoughts to the guitar….that’s where the hunt and peck method comes in. Just experiment…there are no rules. Have fun. If you can record yourself playing and writing, you might surprise yourself with the ideas you come up with. Noodle around on the guitar while recording…then put the recording away for a week, bring it back out and listen. Ideas will pop out of everywhere. Best of luck, and keep practicing till those fingers bleed.