1. Try
If you don't try, you don't know. Rule number one for my students is that we never say 'I can't do something'. As with anything in life, if you don't try something you will never know if you can do it or not. Saying 'I can't do something' means you're just postponing the attempt. If a student says that to me, I immediately add 'yet' to the end of their sentence. 'I can't do something yet' means they aware of an area they need to work on, and reminds them that anyone can do anything with enough practice and determination, if they just give it a go in the first place! Which leads me nicely on to point #2.
2. Practice
Practice is the only way you're going to get better at something. The more you exercise your voice, the more control you're going to have over it. Practice with your exercises and warm ups and then apply to a specific song you’re working on. Can it feel frustrating and tedious? Yes, of course. Is it worth it? 100%. You’ll see!
3. Confidence
This is what I always bring lessons back round to - CONFIDENCE. I have a few students who say to me that when they practice on their own they are able to hit the high notes, sing loudly, and perform the song, but as soon as they try and sing it to someone (teachers, family, friends) they find they can't do it any more. There is a real fear of feeling judged when we sing. It’s a very vulnerable position to put ourselves in - there is no instrument to hide behind. But remember, you should never apologise for what you are putting out there, whether it’s on stage or in a rehearsal room. This is something I have to remind myself every time I sing. Perfection isn’t always what we want. Concentrate on feeling and emotion, and remember that you don’t have to win anybody over. Stand tall and be confident in what you are delivering. You’ll be great.