I think the question has been answered above.
Personally bloody mindedness and perseverence, the will not to give up when it feels you are going no where, being inspired to learn as I was.
Above all you have to have a love for the instrument and celebrate every small success, what matters is the enjoyment that learning brings. for me the first time I learned a tune by actually reading the music was magical, the thought of being able to translate these dots, written hundreds of years ago into sound, is really something else.
I used the Applebaum violin books, and suzuki intonation method. Using too many different learning books in my opinion is pointless, you flit from one to the other, the Applebaum books cover most things until you get the basics.
A forum with frèe online lessons would definately be the best way to improve, but I dont know of any, and if any did exist I cant see how they would work, when would the teacher get the time, to do it, also would it have to be a class lesson, if so his would be difficult as most people on forums live in different ti e zones, great idea though.
Scales, scales scales, as well as arpeggios. and dominant 7ths.
some thoughts..possibly just blather but the way I try and look at learning fiddle
too many resources can muddy things up, I think I agree with that feeling. Im the worst at getting tune books or stylistic books. Theres been some good buys but alot collect dust. Time diving off into another tune or style would probably be better spent concentrating on what i already have. I personally had to make a descision to just concentrate mainly on one style for a while and not worry about the other. Not to say I dont play others from time to time but the bulk of practice is devoted to one style. But, part of that process sorta led into the next point, so ...
Finding what you like and becoming immersed in that style can help. listen to alot of music in the style you want to learn. And when listening try and pick out phrases and ornaments ( if applicable ) not just listen as enjoyment...listen more sometimes to get a feel for more technical things..
Expect your gains to also be followed with setbacks and plataues.. understand that what may seem like a setback or you not getting anywhere is your ear getting better at picking out intonation and other issues.
Dont set your bar up to levels that are impossible atarting out. some of our favorite players have been at it for years if not a lifetime. They put in the work and sacrifice to get where they are musically. Dont think there is some timetable of progress you have to gauge yourself to. Like..oh by such and such month i should be doing this and if im not this must not be the right instrument for me. If you want to learn an instrument, youre on YOUR timetable not someone elses... and im speaking for the adult hobbiest mainly. The younger folks with professional asperations need other input. contradiction I know but I think there is some distinctions that make the situation different.
record often and listen back.. make mental notes of phrases or sections that need work..then actually follow through with working on that before moving on.
I think the forum is helpful in sharing your progress and getting feedback. nice place with people of similar interest. I think it can fill that need for bouncing ideas, likes, impressions off other people and getting input. But only if you use it. Dont be afraid to ask or share.