Sorry, I disagree.
Black and white sand are the worst.
Black will make your tank looking too dark and dirty. It's an unnatural colour.
White will be too bright and bad for your fish.
If you look at the aquascapings done by the experts, almost none of them will use black.
They will use light colour sand such as light brown, yellow or grey.
Light colours will make your tank looks like a river/stream.
Some will use soil(black colour) but the soil are covered completely with plants.
Usually they will put a layer of light colour sand above the soil to cover the black colour soil.
The only people who used black are probably the shrimps breeders.
But they looked ugly to me.
For your background, usually black is the best.
If you can get those black adhesive sticker like Oyama brand will be good.
If not, just use a black trash bag(plastic bag) or black cardboard/paper to cover the back.
If you use paper/card board just make sure they don't get wet, else you may have to change again.
Here are some tips for aquascaping.
To many people, setting up and stocking a new tank can bring a sense of enjoyment and fulfillment as you watch it progress. Aquascaped tanks are some of the most beautiful within the aquarium hobby.
www.fishkeepingworld.com
Aquascaping for beginners: 10 helpful tips that will guide you in making your transition towards aquascaping a little smoother.
aquascapinglove.com
Focus on driftwoods or rocks. Plants are hard to maintain unless you have a lot of free time.
Plants will be used to support the rocks and driftwoods formation (my opinion).
You can try the Iwagumi style (rocks formation) or Biotope, Jungle and Nature aquarium (use nice driftwoods but may not be cheap).
Probably getting some rocks will be cheaper than the driftwoods.
But if you can get a big nice driftwood at reasonable price, then go ahead to get it.
Big driftwood is better than small ones as it will greatly enhance your tank and easier to decorate your tank unless you can arrange them together nicely.
I attached some photos of one of my tank.
It's a very simple setup with only one big piece of driftwood.
The driftwood is the most costly in my tank with cheap sand and rocks.
Try create something that look like the nature will be nice....
Whenever I look at the nature, it really inspires me and makes me more relax...
Summary:
Get a bag of light colour sand + rocks + driftwoods.
Even one piece of big driftwood will be enough if it can cover 2/3 of your tank.
Here are some videos for ideas: