Hey Brad … Welcome to HEF. I use the "new post" button to check in. When you post in multiple places the same question, it clutters up the results. I'd appreciate your restraint.
Working safely under any load is several things.
A stable, level surface. Concrete pad is best, but gravel/dirt is sometimes the only option.
A wide base for the load holder. Goes without saying a jack alone is stupid. ( I like wood block cribbing, stacked log cabin style. Wide, stable, slip resistant) The width of the base is proportioned to the height. A single 6x6 is great for a 6 inch lift. Not so much for a 36 inch lift. Automotive style jack stands aren't usually rated for HE. Besides, metal to metal is slippery. but if you must, a wood block helps.
Always minimize a fall failure. Any jack can fail. But if you crib as you jack, A single one inch of drop is not as damaging as a one foot drop.
Above all else, use the lump between your shoulders. If it looks unstable, it is unstable.