If your just starting to go twice a day, you want to ease your way into it. You don't want to do something in the morning that's going to wear you out make you not want to train for the afternoon.
I would suggest just doing some light work in the morning and your full training session in the afternoon. For example -- mobility, flexibility, foam roll/soft tissue work, and maybe some technique drills with an empty barbell in the morning; then do your full workout for the afternoon.
Here's a blog post by Greg about double-day training:
Keep in mind, whatever your "real life" endeavors include (work, school, travel, etc) will have an affect on your training.