As a construction manager, I can tell you most home inspectors have half a clue at best. That being said, if you don't know much about construction, building codes, maintenance/repair, it is still probably worth it to get a home inspection. He will possibly catch any major issues, although in my personal experience, sometimes they will nitpick on stupid little stuff, and will completely miss major code violations.
In my opinion, if you know anyone in the construction industry who really knows their stuff, hire them to come do it for you. I do my own home inspections now because the issues home inspectors have missed on a few of my purchases have been pretty big ones. Also I'd encourage you to purchase a home warranty. That will cover most of the stuff the inspector will miss. =)
What you can look for yourself: any signs of previous water damage. This is a big red flag. Any crack in a wall or ceiling that is bigger than a hairline should be investigated (might be normal settling, might not). If the house is on a foundation, check that carefully inside and out for damage, settling, cracks. Have an HVAC guy check the air conditioning unit and the furnace (whether or not you get a home inspection, HVAC issues can cost BIG money to fix - it's worth the service call to have a specialist on this one). Check the water heater - assume if it's an older model, you may be looking at replacing it soon. Make sure its exhaust is hooked up properly. Check in the bathrooms that any tile surfaces (showers/bathtub surrounds especially) have all the grout intact. If you see any cracked tile in this area, that's a big red flag (water intrusion/mold is a possibility). Any funky smells should be investigated - mold often has a "dirty mop" sort of smell to it. Run any appliances (dishwashers, garbage disposals...) through their paces. Bottom line, you're just trying to figure out what kind of repairs or replacements you could be in for down the road.
Good luck with your house shopping!