I still definitely have a ways to go, but my therapist recommended this book for me and I find it very practical and customizable, plus easy to read with lots of concrete examples (and cheap!):

The Dialectical Behavior Therapy Skills Workbook: Practical DBT Exercises for Learning Mindfulness, Interpersonal Effectiveness, Emotion Regulation & ... Tolerance (New Harbinger Self-Help Workbook): Matthew McKay, Jeffrey C. Wood, Jeffrey Brantley:

I have used it some on my own between sessions and we've spent some time reviewing a couple chapters as well. I find it very helpful to calm down after painful sessions, and during times when I start to feel very upset and reactive about family situations or other really unpleasant or stressful events.

It is a true workbook, so... about half reading and half filling out worksheets, choosing activities to try, but of course the most important part is using the activities once you select/customize them. Hope it helps. DBT is definitely one of those things where you get out what you put in, and this way, you don't need to focus on the leader or the group structure, etc., you can take what you need here and employ it.

As for flashbacks, there are lots of excellent DBT related comments/threads on myptsd.org, but the recurring theme, which I also find very useful when I have flashbacks, is to engage my five senses and do a reality check. For me, that might be something like:

1. Smelling something strong and woodsy. I keep a bundle of sage at my desk and a bath product that is made from tree resin. Both very grounding.
2. Play songs from my playlist- recent songs that I love, that don't remind me of anything unpleasant.
3. I wrap up in a soft quilt.
4. I remember all the women in my life I've appreciated- my favorite teachers, my counselor, etc.
5. I make myself some hot chocolate.
6. I may try to read a book for a bit or turn on a comedy sometimes.
7. I remind myself the feeling will pass, and don't try to talk myself out of it, but to remember I am safe now, alright now, and do a little fact-checking- it's 2014, I'm safe at home (or whereever) in control, etc.