I work next to a dog grooming shop, so I now know more about taking care of your dog than I ever thought I would know. This post is going to focus on your dog's outer needs rather than the info that everyone already knows or goes to a vet for!
Dogs need their nails trimmed regularly. Some dogs walk on concrete/blacktop surfaces enough that it will help keep them filed down. If your dogs nails are too long, they can begin having problems walking because of it. Trimming their nails is not as easy as it is with a human. In the middle of their nails is an actively live part of their body (that has nerves and will bleed if clipped). Some grooming shops might even dremel your dogs nails. This is a great perk that can allow the nail to be more rounded rather than have a crisp square edge from the fresh clipping. Some dogs don't like the sound, the vibration from the machine, or the heat if it goes just too far. I don't trust myself to be able to tell how far is too short, so I ask my buddies next door to do it for me. It is an inexpensive cost once a month to keep your dogs nails from scratching you, tearing your furniture, and causing them health issues.
Random gross fact-did you know that dogs have anal glands that need emptied from time to time?! This is why some dogs drag their bottoms across carpet. It isn't because they are itching it (well maybe) but the purpose behind it is that they need to empty it and that pressure helps. Larger dogs tend to not need human intervention for this because their regular bathroom habits often take care of the problem. For smaller dogs however, humans can manually help them empty this gland. It prevents a very foul odor from your home or pet to have this done once a month. I had dogs for years before I even knew this existed, so don't feel bad if you didn't know either. Most people don't speak of such matters, but I assure you it is better for me to discuss it with you now rather than your home having that smell because you didn't know your dog needed this! P.S. The best time to do this is while they are being bathed...you need running water to make sure things don't get messy.
Another dog owner piece of information that I think many people are lacking is that dogs with longer hair that need brushed truly need regularly brushed! Some people think that matted hair on their dogs is completely cosmetic and that the dog is perfectly fine. Think of a knot or matted hair on a dog like a knot in a rope. The tighter you pull the rope, the harder it will be to loosen the knot. For dogs, as their hair gets a worse tangle or knot, their skin is getting pulled away from their body more and more. Imagine someone pulling at 15 strands of hair on your head but never letting go! Regularly brushing your dog will help keep this from happening. Make sure you get all the layers of hair too, not just their top outer coat, the undercoat needs attention too. Just like humans, there are many different types of dog hair, so do some research to see what the best type of brush is for your dog.