Tank 2 is
better at display, though. I guess it depends on what you want. My 38
is a tall and somewhat thin, like tank 2, but the environment would
be more stable with the design like tank 1.
The rule of thumb
when filling your tank with fish is one inch of fish per gallon. So
if you have a 10 gallon tank, and you get 5 - two inch fish, your tank
is max-ed out. If you have a 30 gallon tank, you can get 30 -one inch
fish, or 10 - three inch fish and so on...
Be advised, don't
max out your tank right to the hilt. You have taken up room with gravel,
and any other ornaments like rocks or driftwood. Also, the tank won't
need quite as much care if you don't max it out and it will stay healthier.
With my 38, I only added about half the allowed amount of fish. Much
easier to deal with. The environment stays more stable.
One of the things
you may be told is set up your tank, and then after about 4 days to
a week, you can get some of your fish and your plants. That's too soon
for the fish. You should wait at least a month and a half before getting
all your fish.
Another thing that
puts me off is that the store could very easily treat their plants for
snails, but some don't because they said they didn't keep plants long
enough to treat 'em.
The store staff
will give you lots of info on community fish, schools, and loners, so
I'm not going to get into this area too much. Do your homework on what
kind of fish you want.
If you want a suggestion,
I'd recommend White Cloud Mountain Minnows. They like cooler
temps, they don't get sick easily, they don't get stressed easily, eat
almost any fish food, are small so you can get a good amount (Prefer
to kept in school) for even smaller tanks, they are good in a community
tank, and they are beautiful little fish. They grow 1" to 1.5 inches.

Photo of a White
Cloud Mountain Minnow.
Guppies are also
a good beginner fish. Very easy to breed.
If you go with
Neon Tetras, (or Black Tetras for that matter), which seem to be
a favorite, remember that the get stressed real easy, get sick easy,
don't like large water changes, don't like any drastic changes of any
kind. I'm told they like salt in the water, but I find they just
get ick. I have tried to add salt slowly (Total of 2 tablespoons for
38 gallons), taking about 3 days to add it, but I still end up with
ick spots.
If you do use salt,
add half of what is suggested. That's usually about 1 tablespoon per
5 gallons of tank water. I put in 1 tablespoon per 10 gallons
of water.
Depending on what
kind of fish you get, consider getting one or two little Freshwater
shrimp for the tank (as long as you have smaller fish or fish that
won't eat the shrimp). They are awesome. They don't bother any fish
at all, they eat up algae, leftover fish food, decaying plant parts,
whatever, and their feces is easy to vacuum up when doing a water change.
These little suckers are working 24/7.
I have 2 in my 38
gallon tank and 1 in my 10 gallon tank.

A macro photo
(Taken by me) of one of my ghost shrimp. He's cool huh? And just over
an inch in length.
Plants
Get real plants
for your tank. It will keep the tank much more healthier.
Whatever plants you get, try
to stick with the easy to grow ones at first.
I would recommend
Java Moss (Vesicularia dubyana) if you want a tank full of plants in
no time or if you are gonna try breeding This plant grows with no problems,
is easy to take care of, and cuttings grow right away. Java Moss is
like bamboo, grows soo fast, it will overtake the tank in no time.
Mexican Oak Leaf
is easy to grow, cuttings will grow right away, but it won't overpower
the tank like Java Moss will. It will grow long across the top, instead
of growing in a bunch. I am also seeing how well Limnophila sessiliflora
does. It's a really nice fern.