I recently bought a rental property in a different city (across the country), and so far the process has gone pretty well. I use a property manager, and personally I would recommend doing that unless you have a friend nearby who has experience with rentals and would be willing to help you out. It's important for me to know that there's someone local that the renter can call in case there are any problems or emergencies with the property.
If you're worried about expenses, I would expect most property managers to charge you around 10% of the monthly rent. There is also a fee to actually market and rent the property for you. If you're trying to save on costs, you could try to do this part of it yourself before you move away (as long as your able to be there and show the house/unit to people). However, you said you're an engineer, which I'm sure keeps you busy - I'm not sure if you want to be spending your time marketing your unit and scheduling showings. It's also good to have a professional do that and help with the lease agreement. Also, i'm not sure about this, but some property managers might want to be part of that process, because they might want to be involved in vetting the new tenant (and this is also where they make some of their money).
If you have to move for work, will your employer be helping out with your housing costs in your new location? If that's the case, I think you can definitely justify the added expense of a property manager. It will make your life and your transition to the new city a lot easier. Just find a good property manager who cares about your and your property, is knowledgeable and experienced, and who you trust.