I'd like to tell you something about writing good songs.
The Right Moment To Grab Your Guitar And Try To Find Something
Well, I'm quite lazy and before I'm not sure to might find something I don't get up to get my guitar.
It is something you have to feel.
One of the best moments I found out is before falling asleep (especially when you have played with your band this day looking for a chorus for an already existing verse or something like that). It's when you can hear every single instrument clearly. You have to get up and write it down or just sing it to your PC. Don't try to keep it in mind until the next day. Most of the time it's gone.
Another really good moment to pick up ideas is when you wake up. Therefore listen to a record of a band you really like before sleeping. And it has to be the first time!!! you listen to it. Maybe you like the Beatles but you are not aware of their B-Sides stuff and rare songs. Take them! When you wake up try to remember the impression of those songs (and maybe fall back asleep to dream of a melody which is a rare thing).
When you finally get up take your guitar (don't forget the coffee - good for voice) and think of the songs. You can't remember because you heard them for the first time but instead you can find great ideas based on this impression. Try to get a lot, collect them and listen to them all the next day. Decide what you want to keep. Now you can work on these parts or maybe you wrote a whole song but I prefer writing a lot of small parts because they often fit together.
Another moment: Go to your rehearsal room get ready to sing and play and listen to one of your favourite albums (loud) while you sit back and relax drinking a beer. When you're full of inspiration take your guitar and just play. Don't think about where to start. At least one (quite good to brilliant) riff might appear. Or you start singing making your guitar follow your voice and try different chords for the same voice melody.
You see it is all about getting in a mood.
Get Addicted To Your Ideas
Make sure you write one of those songs that are fun to sing. You know, there are songs that make you doubt your singing talent. It's because you can't feel these songs. And then there are songs you get addicted to. When you don't get addicted to your ideas it's probably bad stuff.
Collect Ideas For 1 Song
When you found something you think it's worth to keep of course write it down or record it simply. I used TABs to write down the singing melodies like for example (Beatles):
The rythm is not important to write down because you just need to remember and it comes back. But just record it is of course the easiest way.
What I actually was trying to say is that once you caught one idea (and recorded/wrote down) leave it for a while and then try to remember without looking at your notes. Keep this as well and compare it to the actual idea. Very often there are interesting differences that help you to vary your song. It's quite the same but maybe you take the first idea for the first and second chorus and the alteration for the third chorus. Or you make two songs out of it.
"Steal" From Good Songs
I learned that nearly everyone who is successful "stole" (intentionally or unconcsiously) parts from other songs. Some obvious some tricky. Take three or four (but not too much) notes and give them a new ending or beginning. Looking for a chorus? Try to find inspiration in a verse. If you need a verse try to vary a theme from a chorus.
Another thing you can do is: Transport the atmosphere of a song you like into your own song (for example: Lenny Kravitz - Again / The Beatles - Free As A Bird).
Examples of inspirated songs
Hope I inspired you.