Main tip:
Practice.
If you've never written music before, you won't be writing good music in time for the competition deadline.
If you think you are, then you're wrong. There is a phenominon called "New Musician's Folly" ... which I just made up, but I've seen it a thousand times and been there myself. You\'re proud with your work, so you release it, thinking it's good, when in fact it's utter dog nads. It's just good for you, and your sense of pride and accomplishment disguises this fact to you. People might tell you it's good, but generally these people are either lying to you to spare your feelings, being overly positive about something that's only half decent, or are thick as two short planks.
Of course, it's all relative to which style you\'re trying to write, and your general apptitude for the skills/ear required to write music. If you're trying to write a bit of UK Garage, then be confident you can pick up all the necessary skills in as long as it takes to fall asleep to an episode of Emmerdale. If you're trying to write more complex electronic music, or orchestral, then it will take a long time to make something good.
The other big limitation is samples. It takes years to build up a decent sample library. Buying sample CDs, sampling from other sources, saving, indexing, downloading samples, recording them yourself. There is no one stop shop for all the music samples you need. For your first months of composition, you will be constantly making do with what you've got, and that leads to poor, badly matched instruments and arrangement.
You also need to master the software you choose. Some software is tough to master, and will hinder your creativity. Some software excels with creativity but is technically limited. Either way, you need to learn to use VST/or other style plugins and other effects banks (such as those built into many software products) to make full rich sound. Most people overuse reverb and delay when they start out (assuming they do use it) and mush up the sound scape. Generally, production of tunes (by that I mean mastering to ensure clarity and quality) is very hard to achieve, and in about 10 years of composition, I'm still struggling to get that just right. It's the difference between the equivilent of a muddy bedroom recording of a rock band and the prestine sounds you hear from a professionally mastered CD.
Basically, I firmly believe you won't be able to write good music by the compo deadline if you have no experience producing music, unless you go for very simplified atmospheric styles, or repetative tunes with a simple structure. Both these styles can lend themselves to games, but people will be switching the music off if its not good, or too repetative.
Ok, but now the rant is done, I'll try and think of a few tips for you fool-hardy aspiring game musicians.
-Dont do orchestral. It'll sound crap. It's truely hard to write decent orchestral music with electronic equipment, and requires lots of practice. Also, musically, its the most complex style. You'll need decent pro grade samples, which you cant get free (maybe the odd one or two, but not all you need). So avoid!
-Do write electronic music.
-Do keep it simple and aim for minimalist type styles.
-Start from the centre, and work out. You should create a catchy main section first. Build it up, refine it, and then work backwards towards the intro, and forwards towards the end. If you start with an intro, you are leaving yourself open to a great start and then no room for movement to create the meat. Meat first!
-Spend time matching your samples, and don't settle for some crap. Make sure you put in enough effort to find the right samples, else you're starting with garbage and clashes, and you cant resolve that with composition.
-IMPORTANT: If you're unsure about a bit you've just added to the tune, scrap it. Delete it. Annihilate it. NEVER leave in anything you're unsure about, because the minute you begin to discolour your tune with a few mediocre bits, your tune is condemned to be, at best, AVERAGE. Most likely, if you allow yourself to add crap, it'll be crap. Crap upon crap equals stinked fetid piles of mouldy crap. You have to force yourself to keep trying and keep trying until the bit your adding is good, and if you cant get it right, scrap the whole idea.
-Dont kid yourself into thinking a tune is good when you've finished it. You need to leave it for some time, with lots of playback, to appreciate it from a more impartial point of few. On your first few tunes, you will think they rock, you will think they rock for weeks. It wont be until you outdo them with your next creation that you realise they were crap. And this will continue until you start to reach a platau of skill, when you can get some consistency. Basically, the more time you've spent composing, the quicker you'll be able to realise the TRUE quality of your tunes. I've been writing music for around 10 years, and as such, I am so used to it that I'm normally bored sh*tless of the tune before it's even finished. When you first start writing music there is a buzz which clouds your judgement.
-If a tune is going nowhere, leave it, and start another. You can always come back to it if you get ideas, or take elements from it into your new creation. As long as you start from the middle and work outwards, you'll know if the main hook is going to be good enough before you spend half a day doing the intro. Middle out - make sure the idea is good - then do the rest. If its crap, delete it. If it's ok, but you dont know where to take it, leave it and do something else.
-Never force creativity. If you dont feel like writing music, it will be crap.
-Draw inspiration from sounds, especially for electronic music. When you hear and sample a unique sound, think of how it could form a basis for a tune. It's a great way to do something with a unique hook and get you started.
Anyway, enough rubbish! I'm going to drink beer! Woohoo!