Good singing requires breath support. Unfortunately, this support is often mistaken for pushing or forcing the sound.
Pushing seems easier because it will make you sing louder sooner while learning proper breath support does take time. However, learning to support properly without tension will eventually result in beauty of tone, technical ease and volume without harshness.
Pushing or forcing the tone can cause problems with tuning, create a harsh strident tone and can quite frankly ruin the voice. As you learn to support properly you will be amazed at how much easier it is to sing and how free the voice feels.
One area where it will be very tempting to push is in the passaggio or what is commonly referred to as the breaks in the voice. This is the place where it feels like you suddenly feel you need to use a different kind of voice to sing through it or the voice feels weaker for two or three notes. Others describe it as the place where the voice cracks or switches from chest voice to head voice.
The goal of all singers is to smooth out these areas so that singing feels fluid through all the ranges. When starting out, the break areas may feel weak and you will want to push through them. However, this is exactly what you want to avoid. Working through these gently, will give you the desired result, where as forcing the voice in these areas could result in vocal damage. The key is to be patience. A trained vocal teacher can give you exercises to work on the passaggio.
It is important, especially with young developing singers, not to stress the voice by demanding too much from the vocal folds too soon. Learn to breathe properly and to sing in tune with musical phrasing first, you can learn to fill the concert hall as the voice develops and matures through careful practice with appropriate vocal exercises for your voice, age and experience.
In other words aim to have a voice of quality before quantity. There are lots of voices of quantity. The voice of quality stands out amongst them.