My eyes are going to be 54 this year. While my aim has never been all that great in the 10 years here, I have been getting better over the last few months.
First, there is no substitute for practice. The more you play the better your aim will get.
Second, Many times I've been told "warm up flying against the drones off-line for a bit before loggin on" Even for 15 minutes or so helps, but even 15 minutes is boring as all .... well you know what. It does work tho. Boring as it is, you tend to pay more attention "where" you aim as appose to "just getting the kill before the other guy can". Changing your angle of attack and such can give you more, and better "site pictures". Site pictures are those views you see after a while and just KNOW your not going to miss.
Third, is understanding HOW to aim. In a split second you have to draw an imaginary line from the tail of the plane your after strait through the nose to a point out front of it. You have to aim your plane along this line taking into account how hard you are pulling on your stick as well as the bullet drop due to gravity, pick that one and only spot that matches all the info you have that will result in a hit and then fire. (I don't think it's our eyes as much as we think, all that math for my foggy headed brain could be whats throwing me off!)
As for zooming in. I have mine set for half zoom. I use it when I'm going in on a fairly steady target, buffs, a sleeper on climb out, the occasional vulch
I find that I can ease into those shots and hit very well with some zoom. In a fight on the other hand I have a hard time keeping things steady enough while maneuvering to use the zoom much. Even at half zoom I find it too easy to lose site of the bogie.
For the longest time I was in the 2% hit area (which is about average for the players if I remember Lusche's charts) and figured with the low number of hours I get to play I'd never get much better. With practice and a lot of work I got to hang around 4%. A friend helped me with understanding bullet drop and where to aim better and now over the last couple months I've pushed it up around 6% and can hold it there most of the month.