I know the basics like staying on an axis, placing a block trail, etc, but I always struggle after the first few throws. I usually throw my second eye 1400-1600 blocks from spawn, but after that its very hard to know how much further I should go until another throw. Because of this, I throw a ton of eyes in close proximity to each other until one goes straight down. Although this is my main issue, overall advice would also be great. Thanks :)

https://prnt.sc/tgoq1n What I normally do is I throw an eye, follow it and run for 1k-2k blocks and then throw another eye.

Case 1: it stays in the same direction

• I just run for 100 blocks (more or less) then throw another one and hope that it goes backwards. Now I know that it's somewhere along that line. (follow case 2 from here, otherwise just keep running) Case 2: it goes backwards
• I run backwards and place some blocks. I move away from the line to get a good angle and throw an eye. Now I just need to see where the lines intersect.

If you're still not sure about where the stronghold is, you can still throw one more eye from a different angle and by then you should be sure about where the stronghold is located.

I think Zyrusse's illustration is perfect - the first throw you make creates an imaginary line, and you need to figure out where along that line to dig. The best way to do that is to go along 1400-1600 like you said, but then turn 90 degrees and walk 20-30 blocks before throwing your next eye. The line that the second eye creates will intersect with the first one, and that "x" marks the spot.

Sometimes the second eye basically goes in almost the exact same direction as the first, so you know you have to go a ways yet, then basically repeat.