I make high meat in the fridge, air it 1/day just open it and stir it, eat 1-3 bits and put it back. I usually start with left over meat I've been eating that is over a week old and getting sticky/slimy. Then cut it up and put in wide mouth mason jar, with metal lid.
I toss it if it gets an ammonia smell. I don't think it is toxic, b/c I've forced myself to eat it, and I've never gotten sick, but I don't have to force it when it is regular high.
I think marinating should be held off on until you are experienced with plain high meat. Eat fresh garlic before or after, if that pleases you, but don't marinate until you are comfortable with how a good plain batch high meat, looks, smells, and tastes.
I have never made a good batch from the counter top method. I think it is too quick. It needs more airing, but leaving it open leads to over drying. Fridge is easier to control. Even if you miss a day, just give it extra "air exchanges" until it smells right again.