First off--nothing that I am saying below is new--much of what I've applied I have learned from the gracious folks on this forum. I thought it might help someone starting out so here goes.
I am left eye dominant with little sight in my right eye. I took an archery course in college and I am sure I was the worst student the teacher ever had---trying to shoot right handed did not work for me. Later on in life I discovered I could shoot wheels left handed with a release. Still later I committed to learning to shoot a longbow lefthanded. Things that have really helped me:
Check out the form clock and videos on form on Youtube.
I had no idea what form was as my first bow was 50#. Only after getting my 42# pound Toelke Whip was I able to get back to a solid anchor and use back tension with everything in line.
Tune your arrows---I bareshaft--obsessively and keep one unfletched as a means to check your form or see if anything has changed.
I recently made the following changes that have really helped.
I changed from split to 3 under and from a 496gr arrow to a 412 grain arrow--this gave me a very flat tragectory with a high of 7" at 20yds and a low of 3" at 30 yds. I now aim/gap whatever you call it---don't know why I resisted this for so long---I now have control over the shot. Split was not working for me--this change was huge for me.
After talking with a friend that took a shooting clinic I refletched my arrows so that I now touch a feather to my nose as a means of locating my head in the exact same spot each time---prior to that I was the biggest bobble head out there.
Finally after struggling with right misses (left handed shooter) I focused on tilting my head further over the arrow and the shots came right on target.
What I've found is that this was all something that I had to work out for myself, but again was aided by the help and information on TG. Everyone is different---find out what works for you.
I'm sure that college prof would never buy it that this is now how I spend most of my free time as I'm sure she wrote me off a the kid that would never pick up a bow again.