How deep is the sand you have now?
If it's less than 2" deep, then you can add more sand. If it's a different color, expect they will end up mixing. You don't want your sand to be too much over 2" deep in a small tank as it can pack down and cause issues.
You can plant the tank heavily now if you like. It will HELP the cycle.
What kind of light do you have? If you have the regular 2 socket screw in bulbs, you can swap those out for 2 mini Compact Fluorescent bulbs. I use 10-15w CFLs. Make sure your hood is rated for the wattage. CFLs will grow plants just fine. I aim for around 6500K, but other Kelvin ratings will work.
Try easy low light plants. You can find hints Here on the planted tank section at the top and a ton of plants listed on The Planted Tank Forum site (TPT) as well a Aquatic Plant Central (APC) http://www.aquaticplantcentral.com/f...tfinder/go.php
Java Ferns are one of my favorites.
Bolbitis (African Water Ferns)
And my very favorite Cryptocorynes.
C wendtii is very easy.
Here is a list of possible low light plants.
Excellent List Of Plants For Low Light Tanks - General Aquarium Plants Discussions - Aquatic Plant Central
For feeding your plants add Root Tabs unless you only use Mosses or Ferns that aren't planted (only tied down).
I also use a general plant food like Flourish Comprehensive once a week after a PWC
As far as fish, I like
Celestial Pearl Danios
But I'd do One school of One species.
Then add a couple of Otos or a group of Dwarf Cories if you have room.
Or do a Cherry Shrimp tank !!!! I love mine. you can see my pics on my profile page. Cherry Shrimp are easy and will breed. Ignore the Crystal Red Shrimp for now, not nearly as easy.