It was really frustrating not to be able to finish my songs. I asked myself how all my heroes seemed to be able to never run out of ideas. After all many of them had been at writing music for 30 years, and I was eight months into my guitar playing, so I couldn't be out of ideas yet! I was obviously missing something, so I started to look for advice on the internet. Initially all the advice I found was incredibly unhelpful to a novice. Most guitarists told me to analyze the writing of my favourite musicians and try to think about what they would do, which is easier said and done when you don't know much music theory and aspire to write 20 minute progressive metal epics - music so complicated I eight years later still don't deem myself competent enough to properly analyze it with the attention to detail it deserves. That said I persevered and found some really helpful advice that does not require several hundred hours of training, and I am writing this to pass the information on in the hopes that it will help you as well.
1. The first helpful advice comes from guitarist Lori Linstruth, who means to say that we get so mixed up in trying to write the next epic, perfect song that we overlook the potential of writing a bad riff. When I first read this I thought it wasn't very helpful advice, but the years have proven her right. We sometimes seem to think that John Petrucci can write a piece like "The Count of Tuscany" in his sleep and bring it to the rehearsal the next day. Obviously this is not the case. Most great songs are etched from core ideas, reworked and refined several times before being presented to an audience, and for each idea that gets presented there are plenty of bad ones which do not get to go on display. Since we do not see this multitude of bad ideas we get a weird perspective on writing music and feel much worse at it than we actually are. The best way to overcome writer's block is to allow yourself to write bad riffs. Not only will it be better to practice a bad riff than to practice nothing at all - continuing the song with a bad riff may lead to a following idea that is really good. I tried out this advice and though most of the riffs were either boring, unfitting for the song or too similar to other songs, I found myself writing more good riffs as well, just by letting the creativity flow and allowing myself to write bad parts as well.
2. I ended up with 15 songs which were now finished, but full of "filler" quality material, but that's no good if you want to make a good record. I looked a bit more and stumbled upon an interview by Jeff Waters of Annihilator in which he described how he went about writing songs. As it turns out every time he goes on tour he finds time to write new material. He saves everything he writes and brings it back home. After the tour, when it's time to start work on the next record, Jeff looks at all the riffs he's written and categorizes all of them. Many bands, including aforementioned(-ish) Dream Theater, are known to do the same. If you want to try this, the concept is easy enough. First decide what to keep and what to throw away. Then try to define each riffs place in a song structure, such as "verse" or "bridge." You should now end up with a clearer image of where each riff could fit. Now the tricky part - try to glue the different parts together into finished songs. This is basically a process of trial and error, but it can prove to be very worth while. Personally I ended up with three finished songs out of my first 15 songs, and I still had roughly a dozen great riffs I had categorized and ready for another future project.
I feel I need to quickly deal with some criticisms of this technique of writing songs. Some naysayers and perfectionists will say that gluing music together from individual parts is not "true music" or "from the heart." Now, either these people must be so immensely talented that they never run into writer's block, or they must not get very much done. Either way, I find as little shame in writing good, likable songs that are supposedly not "from the heart" as I do in listening to and enjoying them, and I think there's nothing to gain (especially for a beginner) from an elitist approach to writing songs. Let's be practical.
3.The third piece of helpful advice I found was from Amos Oz, one of my very favourite authors and one very worth while reading if one has time between guitar sessions! Oz had himself encountered massive writer's block, and claimed that some days he could write entire chapters and come up with the most brilliant ideas. Other days he would put two words next to one another and stare at the paper with indifference until his eight hours were up. He would then rise from his chair, tear the paper apart and throw it in the bin before going out to enjoy his free time. The most important lesson to take with one, he said, is that although it may seem pointless at times, it is important to put in the hours (how many that may be) every day, even the ones when you don't feel particularly inspired. If you don't put in the time you will not even have the chance of success, and the chance of success, rather than success itself, is all you can aim and work for. The rest is mostly out of our control.
4. Lastly, some small final advice I have discovered for myself: get to know how you work under different conditions. With experience I have found that I am always at my most creative when I am excluded from the outside world. Sitting in privacy, alone and without distractions I always get much more done than when I'm in a group or when I'm surfing the web while strumming on my guitar. Others feel most creative when they are in a band setting, and hearing their riffs develop across all instruments helps them be creative. What works for you is up to you to discover with time, but if you can you should strive to set up a time and place which works to your advantage rather than against you when you try to be productive.
I hope you found this advice helpful, and the best of luck to all of you who have writer's block standing in your way of making great songs!