Plants take weeks to get used to new tank conditions. So, patience is a must. Newly planted plants will look poorly for a time and die back, but most will recover.
Check the lighting requirements of your plants and make sure you're providing the right amount. 6500K bulbs are recommended for most aquarium plants, because this color value best mimics natural daylight at 5500K.
Large, weekly water changes are helpful because they maintain healthy levels of phosphate, nitrate and sulfate in the water. All are necessary for plant growth.
I prefer liquid ferts, but there are others in granules, dry and tablets. Just dose according to the instructions. I recommend cycling different ferts every few weeks. Plants are much like people, they do best with a variety.
Just some suggestions, there are always alternatives.
"Fear not my child, just change the tank water."