Cleaning your house for sale goes well beyond dusting, mopping and vacuuming. You must clean it like you mean it. You must minutely examine every square inch of your house and restore it to near-new condition. Consider the harsh reality: if something appears dirty or smells bad to you, it will be revolting in the buyers!
The good news is that, as you've decluttered your house, you will find cleaning not nearly as laborious. But just in case, you may want to stock up on your back-pain medicine.
An advantage of a well-cared-for house is that you're less likely to receive a low offer. When buyers can't find faults they focus less on how much money they can squeeze out of you and start thinking that the house is right for them.
If you don't have the time to clean then you should hire a professional. It's a smart investment.