There are some pieces of rat advice I've seen on the Web that, while they make lots of human sense, don't really make much rat sense, to draw an important difference between the two.  Here are my responses.
   

Isolate females when they're pregnant and/or after they've had their kids

Since females aren't isolated in rat colonies in the wild, it's hard to see how this makes sense.  Furthermore, rats need other rats to keep clean, so I don't think it's particularly a good idea to ever isolate them, discounting disease, foul temperament and the like.

So, I split the difference.  I leave one female in Ratville when another is pregnant, and throughout the litter.  I call her the 'nanny'.  She takes some of the burden off the mother by distracting or cleaning the kids, and she helps keep momma clean.  Nor have I ever, ever, had a big squabble between them.  The trick is to have the nanny rat be a docile type, so she doesn't threaten the momma rat.
 

Rats adore cheese

Here we go again.  Some clown at Disney Studios in 1935 decides that mice and rats love cheese and, the next thing ya know, there are a thousand cartoons showing mice and rats loving cheese.

What nonsense.

Sure, they'll take a piece of cheese from your hand, and sure, they'll eat it eventually, but I've never seen a rat go nuts over it like they do for bread or hard boiled egg.  It's just another silly stereotype perpetrated by the cartoonists.
 

Always feed them healthy diets

Jeez, the poor things.  They live maybe two, two and a half years, and you've got Web sites saying to give them rich treats, like cheese, "once a month".  That's like you getting a piece of chocolate cake once every ten years.  I give my rats either a small piece of cheese or bread about every other night.  They also get a handful of 'mixed goodies' (seeds and stuff) about twice a week.  I am not going to subject them to a life of boring food.  If my rich treats shave a month or two off their lives, I'm sure they'll be the first to tell you that it was well worth it.
 

Never hold a rat up by its tail

Uh, why not?  As you know if you're an owner, rats aren't hesitant in the least to let you know when they're in pain.  They squeak the second another rat nips them too hard, the females squeak like they're in pain when the males chase them (even when they haven't been touched), and they squeak immediately if you accidentally pinch their ribs while lifting them.

When it comes to lifting them by the base of their tails, I've lifted all of them that way and not one of them has squeaked yet.  Therefore, I can only conclude that it doesn't hurt them.  And, if it doesn't hurt them, then why not do it?  They honestly don't seem to mind.  They look more puzzled than anything else.
 

Keep everything sterilized

Just think of how filthy a natural rat's nest is.  Absolutely deplorable.  These guys were designed to live in filth.  A rat's version of Heaven is your foul, smelly kitchen waste basket.  While I applaud clean living conditions, I think sterilizing their water bottle with bleach once a week is going just a bit overboard.  I use plastic water bottles in the Water Fount, rinse them out before refilling them, and change them every two months.

As far as the cages go, I clean them out just so they won't smell, not because I'm afraid the gang will catch some fatal disease from their own poop.  And I use 409, not bleach.  I just want the cages to be clean, not goddamn sterilized.  Sheesh.
 

Males and females don't get along
 
This is some serious bull cookies.  In a determined effort to get Matty pregnant, I left her in with Brutus for two months, and I've never seen two rats get along better.

Dogs view rats as snacks

Speaking of not getting along, I grew up hearing about terriers fighting rats for sport in Merry Olde England, so I just assumed that dogs in general looked at rats as cats do.

As such, I was surprised when the rat show I went to was being held inside a building usually used by a dog club.  I actually questioned one of the breeders, noting that I thought it would make the rats uncomfortable to smell their natural enemy all around them.

She just laughed.

A few minutes later, one of the breeders arrived, towing along two big German Shepherds.  I remember one of them walking right up to one of the wire cages and sticking his nose against the bars to get a good sniff.

The rat in the cage bounded over to meet it.  It was quite obvious that it wasn't feeling the slightest sense of fear.

Another good myth, down the drain!