Duke or UNC?
Honestly good books are hard to find, especially textbooks. I am not an economist, but economics books are more similar to math books than anything else.
The only thing that can help is reading a lot, and reading the same topic presented by different people. It also helps to take classes, and to take classes on the same topics, presented at gradually increasing difficulty. It takes a lot of time.
As for linear algebra, when I took it (I was a freshman in college), we used a book by G. Strang, which is a decent intro book. Different people will tell you different books. What is important is that when you a read a textbook, not only do you read, but you do the problems. Being able to do the problems in a book shows a much higher level of understanding than just being able to read the book. I remember I took the linear algebra course over the summer, and I didn't have anyone to work with. I struggled a lot, but at the same time, solving problems in isolation, without any help other than the book and your brain, leads to deep understanding and, honestly, a lot of satisfaction.
I can tell you that linear algebra is probably the most useful math I've ever learned.
Good luck.