Don't. No point hiding the body. A hidden body is a lot more suspicious than one in plain sight. Just make it look boring and pedestrian. Suicides, random attacks in bad neighborhoods, etc. Police aren't psychics, and if you can do it all in a bad part of town, cops probably won't work that hard on the case.

But if you insist that it must be hidden, don't hide it nearby. Take the body, wrap it in a tarp, pile ice on top. Buy a cheap truck (like 2500$) in cash. Call your boss, say you're taking a quick trip, you'll be back in a week. Take your body, keep the ice on it, pile some boxes on top, and leave (I'm assuming you're crime scene is clean. We aren't amateurs here.) Drive the body a few states/ provinces/ regions away. Take it to the ass end of nowhere. As far away from other people as you can (The American Southwest is a good environment for this). Bury the body six feet deep, maybe transplant a shrub on top. It'll die, but that's even better. The smell won't come up, and there's a dead plant on top, no way you'd look there. Wash out the back of the truck, and ditch it somewhere. Ideally a long way away from where you hid the body. Sell it to a scrap yard so they'll destroy it. Go back home, and act natural. You had a lovely backpacking trip with an old college friend. Everyone will compliment your tan.

The best thing to do though is make it look like a suicide, or a random attack. A mugging gone wrong, a raving lunatic, whatever.

If you go the suicide route, make sure to leave a note. Type it up, really messy. Don't say names, just apologize. Say something really cryptic like "I can't live with the shit I've done. What I did to that kid. Fuck, I was so young, but that was unforgivable. He didn't deserve that shit."