What's the best way to preserve my photos?

You have so many options. I would recommend looking at this website and looking around to see what methods would work best for you.

http://www.archivalmethods.com/

It also depends- are we talking about 50 photos? 200? over a thousand?

Probably more like a thousand. Err, more like about 40 lbs when I heft the Rubbermaid container where they currently reside.

Then I would buy one of these boxes- (or something like this- made with archival materials)
http://www.archivalmethods.com/Product.cfm?categoryid=1&Productid=99

Purchase a roll of onion or tracing paper and cut rectangles about the same size as your photos. Insert a piece of this between each photo. It’ll take a while but will keep your photos from sticking. Make sure the paper you buy is acid-free and archival quality or all your work will eventually be worthless.

Cool! Thanks!

Scan them, so at least you will have them digitally if something happens to the originals. I recently scanned my baby albums, so all my baby pics wouldn’t be lost.

Scanning the photos (and/or the negatives, if you no longer have prints) is definitely a good idea, but if you don’t want to throw out your boxes full of physical prints, the boxes listed by @gemiwing are a great idea. My father organized albums of notable family photos in plastic, watertight albums in case our basement floods or something.

I would suggest putting your most treasured photos in albums like that, scanning all of them, and throwing away the ones you don’t want in an album. And of course, back up your photos at least twice.

So many options.

One thing for sure. Throw away the negatives.
You will not use them again and they take up storage space.

Negatives can be scanned and reprinted digitally as well as in the original fashion. Do not discard them!

As the popularity of digital media change, you will have to migrate your archived pictures to newer well adopted media. Pity those whose valuable information is stored on 2120 tape cartridges or mainframe magnetic tapes.

I have so many photos from negatives. Pictures of parties and hanging with friends. Going to the beach and everything you can imagine.
Tons of repetitive stuff. The moment was captured and it is nice to stroll down memory lane now and then.
I was one to believe that is is important to hang onto the negatives.
Being a professional photographer for many years. Only to come to the conclusion that they would never be needed again. So in the trash they have gone.

Now if there are SOME pictures that are unique. You being an artist and such. Or an Olympic event. Then, sure, hang onto the negatives.

Otherwise it is just taking up space. That goes for wedding pictures too. The negatives, if you are lucky to have possession of them. Will most likely never be needed.

Who ever really looks at those after the first year of marriage. Those and wedding videos.
Boring! lol :-)