To the OP - Cleaning may seem like its supposed to be simple, but before I was in the army, I didn't really know how to clean. Until you have a scary seargent coming in checking all the knooks and crannies, its hard to really bring it all home what it truly means to have a clean space... also, if you have a dust mite allergy like I do, you might not realize how much dust can collect in a person's home. So don't beat yourself up for not knowing HOW to clean, its not easy.
One option for you, is not paying someone to clean every month, but maybe just pay one time, and have them come while you're home. Watch what they do, and get an idea of what they do and how they do it, and how quickly they do it. Also, before you hire someone, get a reference, because some cleaning agencies don't clean behind furniture and just do a quickie job - unless that's what you want. You can have someone clean once a year, twice a year, something like that.
I considered having someone come and clean, but I have a hard time paying people $25 an hour to do something like cleaning. My husband also pointed out to me that its ok to have a dirty house - we have a child here, and growing up in a too-clean environment can hinder a strong immune system from developing. One thing I refuse to have people do is take their shoes off in my house - that's a quick way to getting a house that smells like feet, plus human feet are nasty. I don't sit on the floor, eat off the floor or walk around barefoot, so that's something to consider. Keeping a floor clean when you have a husband with mechanic/metalworking hobbies, an 8 year old, 2 cats and 4 dogs, well, making a clean floor a standard would end up killing me.