What worries me most is not whether the people who give advice can or can't sing, but whether they can teach singing. Most good and even great singers don't know anything about how to teach someone else to sing.
That's why my advice here is always "Find a good teacher". Listening to little snippets of advice on a forum is not an effective way of learning. But people still ask, so I give the best advice I can, based on where that person's voice is at now.
And for when you choose your teacher, make sure you hear the teacher's students, not just your teacher. It's how those students sound that tells you how effectively he teaches.
100% of great singing teachers can sing. But only 1% of great singer are great singing teachers. Maybe 5% are decent singing teachers.