What plants are good to use in my tank?
Well these plants below are the kinds I've had in my tank for the past 10 years, and most of these plants came from small plant clusters and have duplicated themselves almost 5-6 fold in a year or less, except the aqautic grasses I have, which has probably grown 20 times more grass than I originally bought in a years time. They don't require tons of light (any good 12+" flourscent bulb will do fine for alot of plants), except plants with a red or purple color, which like more light and iodine supplements(this is a general rule to follow and you'll be fine).

I do recommend short and long tanks because the lighting is then more intense because the lighting is closer the plants. It's good to pick up the a "plant growth" flourescent bulb(s) (do not attempt live plants if you're using an incadescent bulb). Remember plants are great for making water cleaner and healthier for your aquarium inhabitants by adding oxygen. Newts like frogs and other amphibans naturally put out ammonia through their skin into your water, so if you keep fish which dont tolerate ammonia, having those plants in their make the water safer for them by speeding along the nitrogen process (which goes from bad ammonia to bad nitrate to ok nitrates). In a perfect tank you'll have almost none of those, but plants just love to eat up nitrates. If you keep newts, know that only hardy fish do well and make sure not to get aggressive fish that pick on newts.

Underwater Banana Plants
Attractive plants that float with enough leaves providing a floating like lilypad-like leaves with a bunch of bananas underneath. Single strands of root find they're way to the rocks to anchor the plant. ~These are very neat plants but for some reason mine don't ever last for more than a year.
Amazon swords
For your newts to sit, sleep and lay eggs; great for producing places for the newts to stick their head out of water.
Rotella Magneta
Red leaved plants with thick stalks for your newts to climb out of the water, and to add a little color to the aquarium. In general all red colored plants require bright lighting to do well.
Aquatic Grass
This plant produces runners to duplicate(like strawberries), and fills out the bottom of the tank. They need direct lighting to grow. There are many different aquatic grasses from tall and sparse to short and densely packed, but all will do well, and you can really make a nice planted tank with these.

It's a good idea to put a 2"+ bed of small gravel for burying and maintaining plants. In my opinion if you can almost totally fill your tank with plants, you won't and shouldn't have to clean or vaccuum your gravel a all the collected fish waste, fish food, and plant debri make a great soil for your plants(if you do have plants where leaves are seen as dying, covered in algae or seem to be thinning or yellowing, just pull them out. Aquatic plants are VERY forgiving, if you "over prune" individual plants it's usually not a big deal). Everyone may not agree with this, but I have crazy plant growth with no special bulbs, plant fertilizers or CO2 injection system. Newts are alot more tolerant than fish of high nitrate water.