Lots of good advice, I’d add.

Know your fish, their habitat and feeding habits. Some fish live deeper than others thus a fly wont work and a lure or bait and sinker would.

If they eat flies, time of day is pretty important. If you spend enough time on lakes you’ll notice they are pretty active at dusk and dawn. You’ll see them jumping. That means they are hungry and can see well enough to get their prey. Cloudy days are good because they can see out the water all day long or at least when the sun isn’t shining.

In rivers I look for eddies. Places that a fish wouldn’t have to work so hard to stay in one spot. Their there to rest, but if a nibble comes along they’ll bite.

With flies and lures try to mimic an injured animal. If using worms or bait, patience.