Continuing on the subject on structure, it is worth noting some "formal" structures. These are a mixture of old classical forms that evolved over a long time and newer, more constructed forms that were created to help give shape to longer pieces of music.
Sonata form for example is a rather wide term, which can mean different things, but the basic idea is:
Introduction, theme, development of theme, repeat of theme, and coda (which is basically the ending, but can be a repeat of any part of the piece or a even a new bit).
Now I'm sure there will be someone out there wanting to argue that this definition is not correct - and they would correct up to a point. The form I have given above is very loose, and for practical application, rather than historical accuracy. In a Classical sonata form you could argue the case for various repititions and modulations. I have written thei way here just to give an example of a structure that can be used in almost any style.
The aim is to make you think about what your music contains and how you can organise it in a way that will connect with a listener.
Even in very abstract electronic music, you can still use these principles - a theme (or motif) could be a chord on a particular synth sound, rather than a melody in a classical piece. The idea of developing and manipulating the theme then becomes something it is easier to think about. Perhaps in a long ambient piece you could have the theme-chord arrive, dissolve into other sounds, return in a different key, dissolve again then return as it was at the begining.
These ideas are intentionally very simple -as it is quite possible to build very complex things with them.

Another old form is Rondo form. It is a kind of alternation, traditionally described as A - B - A -C -A. The A, B and C refer to different sections of music. You can extend this form indefinately if you so desire (and have enough material). However when extended such as ABACADAEA it can start to get a bit obvious and tedious. Unless the structure is a feature of the piece, you don't want it to be noticable.
There are many variations possible on the Rondo form. For one, can do a Bartok-style mirror image form - ABACABA.
Olivier Messiaen would occasionally use a variation that I liken to a spiral form - A - B - A2 - B2 - A3 - C - A4 ...like a spiral working outward. Each time it repeats a section, that section is expanded. .

Speaking of Messiaen - one of his early orchestral works uses an intriguing form, which has been described as AB (in the Messiaen Companion book) but which I think is more accurately written down as "a-A".
It starts with a long, slow dark melody which drifts alongs and pauses. it is then repeated at the same pitch but in the relative major key - the music is literally and metaphorically transfigured and becomes luminous.

Ok, there is a bit more to talk a bout here but I'm out of time and need to return to Earth. Will follow up shortly.