I generally start out in my sequencer whether it be cubase or the rm1x doesn't really matter.
I have a basic setup for each sequencer so that all my instruments are already mapped and "midied up". This way I can get started right away.
I usually start with drums. I have a bunch of preset drum arrangements that I made for the different kinds of music I do.
Let's say I am creating a trance song. I will load up my default 135bpm 4 on the floor drum pattern and I am all set.
From there it depends on if I have an idea in my head or if I am just going to "fool around" till I spark some creativity. If I have an idea, like some little trance lead floating in my head, I will just get right to putting it down. Many time you will find that when you get an idea down it doesn't sound quite the way you had it in your head. Such is life. But thats not always bad. You are usually still left with something musically useful.
Next I will try to come up with some variations on what I just did. This can be done so many ways. Arpeggiators, effects, midi delays, etc can help you with this. Sometimes its as easy as breaking up the pattern into pieces. Lets say you have a 4 measure arpeggiated trance lead. Take the one of the measures and play it by itself and see if it sounds good looped. If so you can repeat it and use it as a segway into your main arpeggio. Or you can take that one measure arp and use it as a bassline. Hopefully youn get my drift. The most important rule is that there are no rules. Send arps to your drum machine, use a vocoder on a bassline, use fx you normally wouldn't. It's all good when you are trying to comeup with an idea.
Next I would work on drums. Though sometimes I tend to start here as well. Drum programming can be fun and so easy. Source material is important here. Working with plain sounding drums or a GM drumset can be very uninspiring. Load up your fave drum kit in your sampler, software, drum machine, etc and even add some efects if you can. Some reverb and a bit of delay will sweeten things up right away and this can all of course be changed later. Now since i have my four measure trance lead recorded I will loop it and open up my drum editor. I will use loop/record (you can do this in almost any sequencer) and put drum hits in as it records over and over. You can keep adding and removing notes as it records so you get instant feedback as to how it is sounding. A good trick here is to copy the midi notes of the main riff, in this case our trance lead, and copy the notes straight to the drum track. This might give poor results at first but if you play around with it you not only can get a useful drumloop but one that goes well with your main riff.
Woops....gotta run. I was probably rambling here but hopefully you got an idea of what I was saying. If you want me to continue from here just ask and I will do so later.
peace all,
fitz