I like taking pictures with dSLRs. This requires me carrying a big camera. Inevitably, when enough people see you carrying around a large camera, you get asked a lot of questions. While the questions can vary, more often than not I get asked for camera purchasing advice. Purchasing advice can be split into three categories: what to buy, how to buy, and when to buy. Below are some little tidbits that I usually share with people, hopefully it's helpful to others out there on the interwebz What To Buy
The most important factor in buying photo gear is to figure out your budget. Most people pick up photography as a hobby or simply because they want better looking pictures. I think it's important to stick with budgets because, well, we all work hard for our money and these days it doesn't go as far as it used to. Just be realistic: figure out how much you think you'll use it, how much you are willing to spend, and how you can spend. You'll come up with a number. The great news is that digital photo tech has come a LONG way in the last decade, and you can easily get a camera and a lens or two for well under $1000 that will take GREAT pictures. If you end up really getting into photography and really liking it, you can always upgrade later. So figure out a budget and stick to it. Buying a camera is a very subjective purchase. There's no right or wrong camera, rather a camera that's right for you. I always recommend going to stores and checking out cameras in person because I'm big on ergonomics. Other things to keep in mind are size, choice of lenses, image quality, user satisfaction, etc. You can also read reviews on places like dpreview.com, kenrockwell.com, or a million other places on the internet. If you REALLY can't decide on something, you can always rent first. Sites like borrowlenses.com rent out camera bodies and lenses. The biggest thing to remember: better camera won't necessarily make you a better photographer so don't get too hung up on what to buy.
How to Buy
For buying, there are several ways to go about it. Locally, there are "big box" retailers such as Best Buy, local "mom and pop" photo shops, and second hand markets such as KEH, Ebay, and Craigslist. Here are my thoughts from my experience. Big box retailers can be good sometimes, although the selection is often limited and I find the salesmen aren't particularly knowledgeable. They are also going to try and sell you extended warranties, extended warranties for those extended warranties, etc. It can get annoying. Big box retailers for me are great if you know EXACTLY what it is you want. If you're not sure, this might not be the best place for you. Local mom and pop photo stores can be a great resources. The staff are going to be more knowledgeable than staff a lot of other places, they are often convenient, however the prices aren't always going to be the best. I buy at these stores when I need something in a pinch or a high priced item that I want the assurance of being able to return to a brick and mortar store if I need to. Craigslist and second hand markets can be a good resource, but any time you buy used from someone else, you never know EXACTLY what you're going to get. However, if you do your homework places like Craigslist can be a great resource. If you choose to use Craigslist, never give out any personal information unless you have to and play it safe: always meet people in well lit, well populated public areas, bring a friend, etc. Just be smart about it. Another store for used goods you can check out is KEH and there's always ebay.
Buying online you can find great deals on new gear, however the internet can be a big scary place sometimes. The biggest thing to avoid with the internet are "gray market" items. These are new items from the manufacturer being sold in a region the goods were not originally destined for. Often they have great prices, but if anything goes wrong, you could have a lot of difficulty seeking warranty service. Three major online retailers I trust are Amazon, Adorama, and B&H Photo and Video. Amazon has great prices and I have always received US gear from them. Adorama and B&H sell both US and gray market items, but will specify what is US and what is gray market. Most often than not, only cameras and lenses are gray market or US. To see if your online retailer should be trusted for other things, you can always contact the manufacturer of whatever you're going to buy and find authorized resellers. That being said, I've had good luck with Amazon, Adorama, and B&H.
When to Buy
I already alluded to the strides that camera tech has made in the past decade. Technology moves fast and newer, better gear always comes out. Camera product cycles generally range from 18-24 months (although some cameras lately such as the D700 and 5dmkII are pushing 36 months). Something to keep in mind when buying is just do a quick google search on the release date of the camera you're thinking about buying. If it just came out, great, go for it! If the camera you're thinking about buying has been on the market for two years already, you might want to wait until the "new" version comes out. That way, you can either get the new version for usually approximately the same price, or you can find the old one cheaper on clearance. Just keep in mind that time waiting is time you might not be shooting and time you might not be learning to do something you want to do. It's not always worth waiting depending on your circumstances, so just keep that in mind. Sites like Nikon Rumors and DP Review will give news on photo gear and new product announcements, so you can always check in on sites like those too (although that might be overkill for most of you).
Anyway, that's all I've got to say in terms of that. I'll edit this post if anything comes to mind. Just as a disclaimer, I am not affiliated in any way with any of the sites mentioned in this post and as such, I have no conflicting interests to disclose.