Speaking of marking screw holes...
For very little cost, it's worth getting some kind of pointed marking device. Sheet metal workers like to use what they call an "Automatic Center Punch". They usually look something like this...
and run between $10 and $15. That particular one is
available at Amazon for $13. You don't need anything that fancy, but what's $13? Besides, it only costs a little more to go first class, and you're rarely sorry. They're called "automatic" because you don't need a hammer. They're spring-loaded, with an over-pressure release. You press the point where you want to mark, then press harder until the thing snaps. At the snap, inertia and spring pressure combine to ram that point home. It'll put a little mark in the workpiece, which is then where you center your drill and it won't wander on you. It's overkill for woodworking, but it'll be the last one you ever buy in this lifetime unless you lose it.
Serious woodworkers who use woodworking tools instead of metalworking tools usually use what's called an "Awl". They usually look something like this...
and run between $3 and $10. That particular one is
available at Amazon for a little over $7.
Nothing automatic about it. Poke it where you want to make a mark, and give it good shove or tap it with a hammer, depending on how hard a wood you're playing with. Again, very clearly marks where you should drill, and gives you a little divot that won't let your drill bit wander when it first starts turning.
Other things that work much better for locating holes than eyes and pencils include ice picks and nails. Those are so cheap they're nearly free, so I won't bore you with pics or links. Use them much like you'd use an awl, but if anybody asks, tell 'em you used an automatic center punch. They'll be too impressed to ask what the hell that is <grin>