To RebBugler, Born2See and Saddletank:
Thanks for the feedback. I guess I was just frustrated by how difficult scenarios are. I tried Turner's Gap (or whichever Gap) and found it impossible to win after 4 or 5 attempts, bringing to conclude you can't win it. Maybe 5 times more will bring me the needed skill. I had a similar problem with the opening sequence for Antietam in the Cornfield, and the opening sequence for Chancellorsville: succeeded once in the opening Chancellorsville sequence and failed many times, and have never been able to reach objective in opening Cornfield sequence. I guess I have not learned enough and am still a novice. Perhaps I have also underestimated the game's ability to come up with variations and outsmart the human opponent.
As someone who struggled a lot with some scenarios before I got my Gettysburg star I have two bits of advice:
If a particular scenario is being a bastard, do another one or even play some sandbox. I had so many issues with the cavalry stuff and sometimes I just skipped one and then played another one and suddenly some new idea occurred that I was then able to apply to something I was struggling with. Sometimes I just legitimately didn't understand some aspect of the game (that's my current Waterloo issue) or of the sort of warfare I was expected to wage so just experimenting helped a lot. I also read a lot of Wikipedia and a couple of books though I don't know if that helped.
Second bit of advice would be to not keep running your head against the wall. First and foremost I think it's important to just enjoy the game. Consider just doing a sandbox on division level and have fun cursing at your brigade commanders and get comfortable with letting the AI do its thing. Sometimes it messes up and other times it'll surprise you and handle a situation that you didn't even notice. Your brigade commander may have a better idea about what's going on on his turf than you do so let him do his thing. And sometimes you need to take charge yourself.
Basically, enjoy the game and get comfortable with it. It allows for a lot of freedom of play and for me, that's a big draw. But it was hard getting used to, coming from the Total War games.
Edit: not that there is anything wrong with the TW games. They're just very different in scope and that required me to learn a lot of stuff and to unlearn a lot of stuff.
Oh! Also fiddle about with artillery! I find arty the hardest part of the game so get used to it. Practice placing it and look at the lay of the land and consider what you shoot and with what. Again, sand box is your friend.