Depends on who's drafting you and under what circumstances — and what you're willing to pay for it.
Being a conscientious objector is quite easy. You're looking at anywhere from no repercussions to fines to prison time, or even death sentence in some extreme cases. A year or two in prison for a non-violent crime isn't a very big deal, but it's very hard to recover from a death sentence.
Otherwise, the easiest ways out are to be unfit for military service, e.g. to be old, sickly, disabled, or - in some cases - not male.
If you run a business, turn your business into a military supplier and say you need to stay behind to provide goods or services for the armed forces. Become part of the military-industrial complex.
You can renounce citizenship but that's something you should plan years in advance.
If you live abroad, there isn't much your country of origin can do in most cases. I suppose it's possible that your draft dodging could be considered a crime and they'd have you extradited back home on those grounds (same as any other crime), but that seems like a lot of paperwork and legally complicated.