Personally, if I was having voice problems I would not do warm-up exercises before I sang.
There are exercises to do at home which can keep your voice in trim, but you can work out for yourself which ones are most useful to you.
Doing any voice exercises before a performance can strain the voice for an evening.
I found that tension, especially around the shoulders, can restrict the throat and cause strain, thus causing hoarsness - maybe this is where your problem lies.
Nowadays I (nine years older than you) find the simple act of dropping my shoulders and relaxing my arms and hands works wonders.
61 is very young to start having serious vocal problems; maybe you need to rethink your delivery.
The great Sean Nós singer, Joe Heaney remained a superb singer throughout his life by constantly taking stock of where his voice was at and adapting his performance to within his capabilities.
On the other hand, another great (on top form) Irish singer insisted on trying to sing as he did when a young man and completely stripped his voice, inflicting serious damage whenever he sang more than one song.
Good luck.
Apropos of something else entirely, Joe Heaney once complained to us that "It takes me all night to do what I used to do all night".
Jim Carroll