I think the main thing you need to learn is patience!
It's not easy at your age...it took me about 59 years to learn patience, and I still haven't quite got the hang of it
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The real thing is to be very self critical.
Sure your first bow that shoots is great, but a couple of weeks later you need to really study it hard and pick out the faults.
Either re-work the bow or make sure you get it better on the next one. Work hard at 'getting your eye in' so you see the tillering errors early, 'cos that's the only way you can catch them in time.
Think about the finish and fit of every single thing you do. Does the grip really feel comfortable in your hand? If you can actually feel it at all it's not right!
I think we are all trying to help, we can see you making the same mistakes we made as youngsters, but we also see you aren't just giving up like a lot of people would.
So keep at it, try to educate your eye and master those hand tools. The skill and patience you learn now will help you right through your life.
Often when doing jobs the preparation is the key. We see pictures on here asking for tiller criticism with the bow on a wonky tiller with the picture taken at an angle. Get the basics right and the rest becomes less difficult, don't worry that you may only have hand tools, just about everything can be made by hand. I recently cut a 32 tooth gear for a lathe all by hand... I could have bought one... but where's the fun in that?
Del