Scanning Photos and Documents

I am not a pro, I just read enough by googling for information to get me started then I go until I get stuck and have to ask a question.  Here's what I do to scan photos and documents.

First of all I almost always scan in color, 48 bit or whatever the highest number choice is. Why?  Because bigger is better of course!
I do most of my scanning in .bmp format.  From what I understand, that is good if you are going to want to edit later.
I will make a second scan immediately in jpeg format if I know I'm going to upload it.  Some sites require that file size not exceed a certain size.  Find a Grave has a 500 kb limit.  Ancestry.com has a 15 mb limit.  Some sites only take certain formats but I have yet to see one that doesn't take jpeg.
So usually I will scan an image up to four times depending on what I think I will do with the photo later.  It's easier to just do it in the first place.  If you only want to make one scan do it in .bmp and save it later as a jpeg if you need to.  DON'T do it the other way around.  JPEG format compresses the file, meaning information is lost and you can't get it back.
Now on to resolution.
First of all lets talk about the average snaps we all take on vacation.  Not good enough to frame but still good for memories.
4x6 and smaller - 150 or300 dpi
5x7  or 8x10 - 150 dpi
 Every once in awhile (1 in 100 or maybe 1000 for me) there's a shot that deserves to be framed, copied, given as gifts and entered in a contest.  Also into this category falls the old photo of Aunt Maud that turns out to be the only photo she was ever smiling in and her face is about the size to a pencil eraser.
Scan these at 600 or 1200 in .bmp.  These will result in HUGE file sizes and may need to be stored on a cd or someplace other than your computer hard drive.  You shouldn't store them there anyway any longer than you have to.  It really stinks when your computer crashes and you have to pay Best Buy $100 dollars or more to retrieve your information.  Easier to just store the files somewhere else.
With a file this size you have the flexibility to enlarge, edit and crop to your hearts content without having to worry about pixelizing (can you believe it, pixelizing is not a word!).  How about pixelization? Nope, that's not a word either.

I store all my scans unedited.  That means that when I edit, I SAVE AS not just SAVE.  That will ensure that the original file stays intact.  So now your 40MB scan is taking up 80MB of space.  Think of buying an external hard drive.  I have a 2Terabyte one that I love.  I can save directly to it and just plug it into whatever computer I'm using.
To reduce file size I crop before I scan when I can.  If I'm going to pull one face out of a class photo, there's no point scanning the whole class.  If I think I may want it for reference I may scan the whole class as a low resolution jpeg file, which will show up just fine on the computer screen and even printing.

There are other formats that I don't use much but may be good to investigate.

As far as what scanner and program.  I am currently using an Epson Perfection which is definitely not high end but it does a great job for me.  I have also used HP and Mustek with good results.  Usually the scanner program that comes with the scanner works great.  If you scan something from within a program and you are not getting the results you want try scanning from a different program.  I was surprised at how much difference there can be.  I do most of my editing in JASC Paint Shop Pro but I've been learning to use Picasa from Google lately and really like it (especially the price..FREE) That program also has facial recognition capability and is great for making scrapbook movies for birthdays and weddings and stuff. Every program has their ups and downs.

A word about document scanning.  The most important thing is to make sure it is readable and that you can enlarge it a little bit.  I never scan a document at less than 150 dpi.  I usually scan at 24 bit color and .bmp.  If it is to just make a copy of something not being kept try 72 dpi and jpeg and gray scale.  If it works, great. I rarely get good enough results with black and white setting.
I treat important documents like photographs.
This is one that I scanned at 1200 dpi then edited and saved as to get a 2 mb file (was 40 mb)

original scan
cropped and rescanned, edited and saved as to get a reasonable size file.