A song structure can often be a difficult thing to get right. Do it well and the song will seem slightly too short and anyone listening will immediately want to listen to the song again once they have finished, the transitions will be seamless and there will be a perfect balance between tension and release. Get it wrong and the song will sound boring and overly repetitive, the transitions from between different parts may not sound right and consequently the relationship between all the musical elements may not really work in the way you had hoped.
So how do you aim for the first outcome rather than the second?
There's a few tricks I have learnt along the way that greatly help with this problem. For example, I tend to find that writing music and writing something like an essay or short story use similar skills in this regard, so if you can take the time to write every now an again (say if you are studying and need to submit a piece of written work for example) then this is obviously good practice, and you should use it as an excersise to sharpen your storytelling telling skills which can then be applied to music. Simply put, an essay or a short story can use similar structures to a piece of music. It has an introduction that sets the tone, a plateau or middle which should have some interplay between between different characters, ideas or themes, and an ending that concludes the story or issues explored but, crucially, which also leaves the reader with some questions and might provoke some curiosity or further thought. This last point goes back to what I mentioned previously where, in musical terms, the equivalent would be if the listener feels the arrangement is slightly too short and will immediately want to listen to the song again.
Aside from writing, which if you are not in the habit of doing can be difficult and tiring, simply listening to and analysing music can be a powerful tool for identifying song structures that work, as well as tools for building tension and change within that structure. If you are into making music, then you now doubt already do this. So if you've identified a song structure that you like, take this a step further and use it as a reference song by dragging it into your Digital Audio Workstation (DAW) and cut it up into sections according to the changes in structure. You can be as detailed as you like with this, from focusing on half bar sections where transitions happen to simply identifying phrase changes, which, depending on the reference song, may happen every 16 or 32 bars. Now colour code these sections and arrange your ideas accordingly, that is to say using the reference song and different coloured sections as a guide for when you should be changing elements in your arrangement.
As long as your musical ideas are different enough from the reference song there is no possible way anyone should be able to identify the fact that you've used it as a guideline. If someone does identify this then they've spent way too much time analysing both your music and the reference track you've used, and you should probably discount their opinion anyway. This technique is an extremely useful tool used by plenty of professional artists. As you get more confident with song structures and you practice writing music more and more, you will eventually be able to do away with using reference songs all together. In my opinion though, you should never stop analysing other music in this way and identifying the tools for change that other artists use in their music. This will always allow you to converse better musically with your listeners.
If you are interested in finding out more about song structure and what makes a successful arrangement, check out the "Essential Secrets of Songwriting" blog here, which I highly recommend.