Roman
Perhaps the best way to shop is to define your needs, set your priorities without regard to brand, then shop for the combination of body, lenses and accessories that best fits that need within your budget.
Then - as I said in the previous message - get hands on in a camera store.
Do the controls seem confusing or awkward? Is viewing clear and bright? Does the camera body fit your hands, feel balanced and handle well at low shutter speeds?
What level of automation do you want? If you plan to use the camera on full automatic, you might be happier with a high-end point and shoot than a low end SLR, though P&S does not do macro. My "normal" lens for the F3 is the superb 55mm MicroNikkor which is great for both normal lens photography and macro. The current version is a 60mm lens, also highly reputed.
Do you really need an SLR? Have you considered a rangefinder camera, now that they are proliferating again? Compact, quiet, easy and precise focusing in low light. Very unaggressive for people photography - far superior to SLRs in this aspect. For landscape photography, Voigtlander has 12mm, 15mm and 21mm superwides that actual mortals can afford.
Have you considered digital over film? You can shoot freely without even thinking of film and processing costs. I have owned two Nikon Coolpix cameras and both paid me back in a few months considering the number of shots I took and what it would have cost with film. I love the fact that I can instantly review my settings and make adjustments to get the highest possible quality, right on the spot.
My Nikon digital is legendary for macro photography, and I love it for landscapes.
http://www.larry-bolch.com/desert2002/
It is also a superb camera at night.
http://www.larry-bolch.com/ephemeral/
For me, the upside is that I get complete control of the whole image-making process concept, exposure, processing and presentation. My run of the mill prints are the equal of the best of my professional portfolio shots, but then I do know image processing quite well. With digital, I hit it first time ever time, while the portfolio prints took days and consumed a box of paper and the chemistry to process them. I print my five megapixel images up to 13" x 19" - 239mm x 483mm.
However, for many, this is also the downside. If you want to just drop off you film at the one hour lab and let the operator and big machine do your interpretation for you, this becomes a lot less handy with digital, though more and more processors also do digital snapshots now.
http://www.larry-bolch.com/film-vs-digital/
As per learning from mistakes, no, I really have not. Money for equipment has always been carefully budgeted, and no equipment is bought until the needs are clearly defined. Once defined, then it has been a matter of looking for the best specific solution within the budget. I have never purchased equipment on a whim. Though I have bought a lot of cameras over the years, none has been a disappointment.
While I have had excellent service from Nikons over many decades and can highly recommend them, it is well worth thinking outside of the box befor buying. If you keep coming back to a Nikon SLR after checking out each other alternative, then you can go ahead and buy with confidence. It is well worth the time and effort.
larry!
