It's funny to think about being sure to have enough fuel since I almost always have multiple bags of charcoal on hand, but sometimes running low does happen.
I'll add a recommendation for safety, especially when burning charcoal or wood. Long sleeves shouldn't have big, loose cuffs (but since it's not 1974 this isn't a major problem) and long hair should be pulled or tied back, and I always wear shoes. And a fire extinguisher within easy reach is never a bad idea, especially for those who're just starting out with live-fire cooking.
Thick leather gloves like welding gloves are a must, as are a spare set of tongs dedicated solely to fire-tending. And that fire extinguisher is still a must whether you've been grilling for a week, or 20 years. Accidents still happen.
I don't have the leather - I use silicon. I do have extra tongs but use a long handled slotted stainless steel spoon to move my coals.
I always keep a good supply of charcoal on hand. I've been on the grills so much in past 30 days that I've had to open my 4th bag of charcoal since mid-June this past Sunday.
I switched to leather after I watched a silicone glove burn up when a friend somehow spilled a few coals on one from a chimney and melted it (his hand was OK, though). Silicone is OK for high indirect heat but not so good for direct heat. I pick up live coals with the leather gloves sometimes (in emergencies only).
And the same for me with charcoal. I grab a few bags on sale even if I don't really need them, and I keep them in a sealed and weatherstripped spare plastic garbage can with a bit of dessicant inside (basically a can or bag of silica gel). I ran weatherstripping over the top rim of the can, and it seals it beautifully.
The dessicant keeps out the ambient moisture and keeps the briquettes dry literally for years if you reactivate it periodically. You can reactivate the silica gel just by drying it in the oven. Plus, silica gel is what's in those little baggies that come with electronic equipment and some appliances, so it's easy to find and collect.