Preparing for a trip is always difficult, as my job involves a lot of sitting behind a desk its a question of time, motivation and the activity undertaken. I'm not a professional trainer so I can only tell you what I do
A few years ago I invested in a cross trainer - one beefy enough that I could use whilst carrying a rucksack, my main traning therefore centres around this. I have a 25lb training pack that I wear whilst on the cross trainer, which I use in 1hr stints.
I don't like training - but at least with the cross trainer I can watch the telly at the same time.
I like playing squash - so use this as my training whenever possible. Squash is intense activity so a 45 minute match involves a lot of effort - when using the cross trainer its also important to put effort in pushing yourslef gives you the best workout.
Then there's no real substitute for walking - especially uphill. The only significant hill I live near is called Roseberry Topping - I can climb it and return to the car in an hour - and it takes me half an hour each way from home. So I can get an hours realistic training for a two hour commitment.
I can usually get out once a month for a days walking and sometimes an overnight - do as much of this as you can - carrying a heavy rucksack even though you don't need it.
In summary then I have three main areas of actvity, Cross trainer, Squash and getting on the hill. In an ideal world I'd be on the hill every weekend - but this isn't practical for me. I therefore plan to do one activity 5 days out of the week - so I'll either play squash, spend an hour on the cross trainer or go for a strenuous walk (a full day or sometimes a very strenuous hour). I'll probably up the anti as the trip gets closer depending how I feel.
I can tell in the first few days of a walk if my training has worked - it makes a big difference to how I fell.
I have some previous experience with an ice-axe but had never used crampons in anger - so I signed up for a two day winter skills course in Scotland in the January prior to my MBC. This was time and a relatively modest amount of money well spent as it meant I knew what to expect when I got to the mountain.
You could turn up with no experience of these whatsoever - but I'm glad I did this course beforehand.