It's one of the most commonly asked questions by new photographers.... and it's a question even pro's have trouble answering.
What should I buy?
Let's be clear, that's a personal choice and I'm not going to tell you! Instead, I'll offer some suggestions based on my experience (and personal purchasing mistakes)!
You won't have to look far to find someone debating the issue of camera brands on the Internet. Nikon and Canon are the largest camera companies for purchasing a SLR camera, but other brands offer an ever growing line of competing equipment. My advice: buy either Nikon or Canon. The problem with the "smaller" brands is that you won't have the same availability and diversity when it comes to lenses. This is particularly true with specialty lenses like super telephotos. While it might not apply to you currently, you'll be glad to be carrying one of the big brands when you start looking for those lenses. I'm not saying Fuji/Pentax/Sigma or any other company doesn't make great gear - they just don't have as many choices available.
Nikon or Canon.... the debate continues. This is one of those classic debates, like Coke or Pepsi / Honda or Toyota. Each side clings to their brand and touts it as the best. Look at the pros.... they shoot both.
I particularly enjoy hearing one side claim that their company makes better equipment for a particular aspect of photography (example: Canon is better for wildlife). I don't think there is any substance to this argument and dismiss these claims. When it comes to picking a brand, base your choice on the feel and fit of the camera and how you like each one. Compare similar makes between each other. I choose Nikon because I liked the button layout, feel, and design, but you're not going to see me touting that Nikon is the best thing since sliced bread.
Be willing to commit to your choice though! It's hard to switch between brands since lenses are not interchangeable, so choose one and stick to it!
Buy Nice Lenses, Dammit!
Most people get sticker shock when they think about spending $2,000 for a lens, but they'll chunk out that much for a camera. However, your camera sensor is only as good as the glass in front of it.
It's worth repeating: Your camera is only as good as the glass in front of it.
Be prepared to spend as much, if not more, in lenses than your camera. The camera will be out of date and replaced with a new model in a year.... if you buy nice lenses, they will last you for decades and may even become more valuable. Lenses are an investment, cameras depreciate very quickly.
If I had a tight budget, I'd buy a nice lens and a mid-quality camera body to start, then upgrade the body later. I can actually see the difference in my photos when I use my high quality professional series lenses and when I use the cheap ones sold at Best Buy. There'a a reason the Nikon 24-70mm costs as much as it does.... it's a spectacular piece of engineering and glass.
Take the Internet with a Grain of Salt (or Two)...
The internet is full of bloggers and equipment reviewers. Some of the most famous are folks like "Fro Knows Photo" or Ken Rockwell. While these sites can have good advice, I recommend taking it with a grain of salt. You wouldn't ask someone like me (a landscape and wildlife photographer) for advice on photographing babies or weddings, would you? Look for people who shoot the same sort of subjects that you do and then look at what they are using. Even bloggers like Ken Rockwell have a bias; recognize that bias and don't let their bias influence your purchases. The best advice will come from people who have work similar to yours or who have a style you'd like to emulate..... not someone providing generic "one-size-fits all" recommendations.
Also be leery of anyone who is paid to review something. None of the reviews I do are solicited; I'm not paid or given free equipment. I talk about the things I like and don't like without fear of blow-back from a company. You don't have to listen to me, but find someone who has a similar philosophy to their reviews.
OK, you made it this far. So what would I recommend? If you were just starting out, I'd recommend a nice lens (duh) like the 24-70mm. This will cover a wide array of photography and you can always zoom to get closer to the subject by taking a few extra steps with your feet. I avoid "travel" lenses that are designed to be one-stop-shopping lenses like the 28-300mm. I've had bad experiences with their quality and would rather save the money for a nicer piece of glass.
Don't forget about 50mm. That's a wonderful lens and you can buy a high quality 50mm for very little money.
There's little point to recommending specific camera models to you because it'll be out of date before I can click publish on this blog. I started shooting Canon and switched to Nikon shortly thereafter when I upgraded to a semi-professional camera. That upgrade got me weather sealing, metal body, speed, and functionality not seen in my entry level camera. Both Nikon and Canon make wonderful semi-pro cameras for around $1,000.
One tip is to consider buying used. Because SLR camera technology evolves so quickly, you can find GREAT cameras for a fraction of the price if you buy used. I'd recommend checking out B&H Photo Video for their selection. Most beginners won't miss the small upgrades seen in new cameras and will be quite content to learn on a slightly older camera. You can find photos taken with the cheapest of cameras on the front of magazines, don't feel pressured to buy a nice camera if you can get the same results for less!
The best investment you can make when it comes to photography is to invest the time to get better. Go shooting every day, even if it's just in your back yard. Try a new technique. Try pushing that button you've never used. It doesn't matter - you'll benefit from the practice.