I often get asked what can be done to sound better and be a better singer. The answer is simple:PRACTICE OFTEN!
Once you have learned the proper technique for singing, it's just a matter of making it a habit. You need to take it from the conscious mind to the unconscious. It HAS to become second nature.
I just spent an hour on my roof area singing Christmas songs and set songs but didn't have to remind myself to use diaphragmatic breathing. I converted to it over 7 years ago. At first, I DID have to remind myself to push out my belly and keep my shoulders down whenever I inhaled but now it's pretty much automatic. It's no longer a conscious effort and I can just focus on the song, not my technique.
Consistent practice is the secret to singing better. Try to sing something each day.
Merry Christmas and lift your voice up to the Lord. There is no better time to sing than today.