Top ten Gerbil basic do's and don'ts
1. Do keep gerbils in pairs -- gerbils need to have a gerbil companion.
2. 
Do not put stranger gerbils together without careful and gradual introduction; they will fight violently.  Two gerbils separated for more that 24 hours are strangers and must be re-introduced.  And never let your gerbil "play" with your hamster, bunny, or other pet (someone will get hurt).
3. 
Do check the water bottle every day to make sure it has not run dry.
4. 
Do feed a quality seed mix specifically for gerblis that has oats as a main ingredient, not any/much corn, 15% protien, some sunflower and pumpkin seeds and lots of variety. I feed a fresh, home made mix from JandEm Gerbils Another option is 1/2 oats (rolled or old fashioned oats NOT quick oats!!) and 1/2 cockatiel food add some ferret food or rat mix to bump up the protein for nursing moms and growing pups.
5. 
Do give your gerbil plenty of cardboard and wooden toys to climb on and gnaw up, otherwise their teeth will become overgrown and they will get bored.
6.
Do not keep your gerbil's tank in direct sunlight or exposed to drafts.  Provide a small box or other place to hide and sleep in.
7.
Do make sure the tank is covered and clipped at all times.  Gerbils are great climbers and jumpers and love to come out.
8.
Never hold or pull your gerbil's tail (except at the base right near the body), it could break off. Do not use a wheel with open slats, as it could catch your gerbil's tail and break it off.
9.
Do use for litter about 3 inches of Carefresh or Aspen or corncob. For bedding add unscented toilet tissue or paper towels shreaded.  Avoid materials or anything with fibers (including the "fluff" sold in pet stores!) which can get caught in their toe nails.  Cedar shavings which have harmful oils. Pine isn't good either for gerbils (may cause allergies).
10.
Do clean out the cage every two-three weeks. Many people use vinegar or a bit of bleach & rinse well with hot water.
   Need more information on Gerbil Care?
Go to AGS Care Handbook or  National Gerbil Society FAQs
And find out whether your gerbil is a boy or a girl --
2.4 How do you sex gerbils?
How to introduce two gerbils --
2.7 How do I introduce a new gerbil to my old one?
What to feed your gerbils --
4.1 What do I feed my gerbils? And many other important gerbil facts.
How I create a Simulating Environment for a same gender pair
I am always interested in seeing how people create a stimulating environment for their same sexed gerbil pairs, specifically within the constraints of a 10 or 20 gallon sized aquarium.

My very first gerbil -when I took her home was in a ten gallon aquarium that was filled to the top with several months worth of gnawed cereal boxes, and she had created a tunnel structure on multi levels similar to that describe at the web site --
http://www.rodent.demon.co.uk/gerbils/burrow.htm

So this was my first image of how gerbil housing should look, rather than the inch of bedding and little/no hiding places that you see in pet stores and gerbil books.  Following this idea of levels, burrows, and self-gnawed bedding, this is how I've been setting up my tanks for my gerbils.  Two caveats are: #1 a breeding pair with pups needs to have nothing but a few inches of bedding to keep the pups safe from being suffocated, squashed, or lost. #2 Too many compartments could cause territorial disputes and fighting, especially with a group of gerbils (more than two).

At the bottom of the tank, I tape together tubes (wrapping paper, paper towel, and/or toilet paper), next to that I put a three tiered dish rack I bought a Walmart, then on top of these I put about 4 inches of bedding material (I was using pine, and switched to Carefresh for safety). This can be expensive in the 20 gallon tank, so I wedge a cereal box in the middle and have one side only be the layered, burrowing side, with just a little bedding on the other where I put the food and water and things to gnaw -- they seem to love the challenge of climbing over the cereal box to get from side to side, even when there is a hole to go through it.  And now on the layered side, I wedge a few cardboard boxes to create more layers on top of the lower layer.  Also egg cartons (once gnawed up) makes good burrowing substance. To give them a challenge I'll tape the egg carton closed, put treats inside and start a little hole for entry. I also give them a sturdy box about 4-5 inches square to nest and sleep in (they've never slept in any other part of the environment -- this seems to be very important to their security, and they run into the nest-box if startled).

As an interesting aside, Blossom and Cara the two gerbils we got at 8 weeks have been used to a layered tank since then, and like to nest at a high level.  Whereas Alan, the gerbil we got at 4 months who was used to the pet store 1 inch of bedding environment is a bottom dweller who will only nest/sleep on the bottom level of the tank. When I paired two of these, the high-level female joined the bottom-level male in that nest box.

They create quite an interesting structure from this initial setup -- they seem engaged by it and it is fun to watch. I also introduce something new every couple of days. A small tissue box with half the tissues taken out is a big favorite; or paper towel rolls with 1/4 inch of paper towels still on. They also like those roll-a-nest balls. After two weeks I clean out the cage, leaving a few of the pieces in tact that are not smelly or too gnawed up. I have not found the potential problem of the gerbils getting less tame in a burrowing system -- mine climb up to the top surface to get sunflower seeds or crawl over the side once I have the top of the tank off for a few minutes. Perhaps this is because I remove the structure after two weeks (and it's pretty much gnawed away at this point) and they start building it over, versus keeping it for an extended period.

I love the set ups at the web site below, although way beyond my personal time available for creating and cleaning gerbil houses...
http://www.maisel.de/~eva/cages.html
Basic
Gerbil Care
Basic
Gerbil Care
New York Gerbils builds wonderful houses for their clan: http://gerbilized.tripod.com/gerbils/id20.html
  Though I recommend masking taping the slated wheels or a solid wheel:
http://www.transoniq.com/
Nice Housing Setups that you can create for your gerbils
Untitled Document

My Sample Housing Setups
Click here to see samples of my gerbil housing - I can clean out my setups in less than 10 mins.