I was terrible with money until I got out of college and had to live on $8 an hour. It'll come with time and yes, not having good financial role models does not help. That's why I got my act in order so D7 and D11 have a good example to follow on finances.
The Dave Ramsey Financial Peace University class really worked for me -- and I knew all of the concepts. I just needed it drummed back in my head.
Check with churches in your area. One might be offering it. If your sister gets her act together today she'll be fine.
Me: 47, Ds 17-13, D final 6-11 http://tinyurl.com/yk4e2tz http://tiny.cc/thread2 http://tinyurl.com/ydtphqu http://tinyurl.com/thread4 http://tinyurl.com/3sm78k6 http://tinyurl.com/thread6
