Steam. Steam. and More Steam.
Some people think that you need to take your suit to the dry cleaner after every one or two wears (suit, sportcoat, trouser), this is not the case.
Unless you actually spill something all over your garment, you don't need to take it to the drycleaners. How does it get cleaned? Steam.
If you don't have a steamer, go buy one- they aren't expensive. Bed Bath & Beyond has some good ones for $80+. But THIS is how you clean your garment.
All the dust and dirt that may float onto your suit, maybe even a little sweat that drips into it- can be cleaned by using this simple machine. As the hot steam engulfs your garment it disintegrates all those small particles, leaving you with a nice clean suit.
The problem with the dry-cleaners: Your suit no matter what quality has a shelf life dependent on dry cleaning. It isn't good for it, the chemicals, the sprays, the pressing...the process wears down the garment quickly. Having your own steamer is the perfect solution to this problem. Especially if your garment is cheap, you will notice the shelf life on that start fading away around the first dry-cleaning.
Here are some examples of what happens to suits if dry-cleaned too often:
If you want to take your suit to the dry-cleaner once a year, then that is fine. A lot of people say "make sure to take your jacket in with your pants so they fade together in the same manner." This is true- if you dry clean your garments ALL THE TIME, yes do take them in together. But if we are talking just a few times, the difference is not noticeable, don't worry about it.
If you were guilty of cleaning your suit after every wear- I just saved you a ton of money. Cheers!