1. The Lighting
As with all great photography, lighting is key. The best lighting is always natural light that you find outside. If you're lucky enough to get a lot of natural light from indoors, then that's perfect, or you can try an overhead white light. I like to take my flat lays on my front porch around twilight hour. Forget using flash on your phone (although flash on a DSLR might work on occasion).
2. The Backdrop
All you have to remember when it comes to the backdrop is to keep it simple. This way, all of the focus is on the item(s) you're trying to highlight. Do this by using one of these three backgrounds: white cardboard, fluffy white throw or dark wood floors.
This is where things can get a bit challenging. You have your background and the lighting is right, but now it's time for the meat and the potatoes: the actual items. Be sure that you space out each piece so that nothing touches (some exceptions). A good way to accomplish this is by being meticulous about the amount of products in your flat lay. Stick with anywhere from three to six pieces, preferably in the same color palette.
It's your Instagram so feel free to deck it out with whatever items that suit you. But I find that there are a few items that tend to work really well for flat lays: clothing like tops and shoes; magazines with laptops; food and coffee; makeup and jewelry; flowers and perfume.
Last, but not least, don't be afraid to use a photo editing app to get rid of any weird shadows or to add a touch of brightness. You can stick to the filters on Instagram or get a little fancy. Just decide if you want an Instagram that is more colorful, or with more pastel hues, or simply monochrome. Try Camera360, Afterlight, Snapseed and Square InstaPic.