Growing your nails can lead to great improvements in your sound. It also creates a number of complications and without care, your nails will make it harder to play guitar. Rough nails can also make it sound like you are scraping them down a blackboard.
Beginners should not grow their nails, it is much easier to learn rest and free strokes without this complication. Young players may find they are not permitted to grow their nails because of school sport commitments.
It is important to understand how your fingers travel across your strings. The string starts by making contact on the right hand side of your fingertip and travels across your fingertip to the left. The string does not play until it leaves the finger or finger nail.
The string should not encounter any resistance. Any nicks or rough areas on the nail edge will be heard as a scratching sound. You should ensure the edge is as smooth as possible. Some guitarists use super fine glass paper (1200 grit or finer). I am happy using a selection of standard nail files and buffers.
The string should also travel across a flat surface. A curved nail can actually catch on the string. The extra resistance will slow you down. Start with a fairly short nail and keep the end flat. Study how your finger comes into contact with the string and travels across it. You may then wish to experiment with the slope of your nail, either sloping up to the left or the right. It is impossible to offer an exact nail angle because it depends on your right hand position.
There are extended notes on nail shaping in Scott Tennant's Pumping Nylon. It will certainly give you plenty of guidance on nail shape, but you should still experiment. I prefer my nails a little longer than Scott suggests.