How should I practice between two sessions?

"Begin at once to live, and count each separate day as a separate life." Seneca

If you want, try to meditate informally throughout your day, as briefly as you like:

• Choose a daily activity that you normally do mechanically, simply part of your everyday routine. This could be something like getting up in the morning, walking along a corridor, taking a micro break at work, stretching, brushing your teeth, taking a shower, drying yourself, getting dressed, eating, driving, taking the bins out, going to the toilet, waiting for a red light, doing the shopping, getting in the lift, stroking the cat, sitting at your desk or on a commuter train... or many other things.
• During this activity, deliberately try to increase your consciousness of each moment, every second, as if time was slowing down and your consciousness could carefully contemplate every aspect.  Don't carry out the activity more slowly or more carefully. Keep it natural – be yourself.
• Simply observe yourself. Take the time to notice the tiny sensations or changes in your body, your thoughts and emotions as you do this activity. Watch yourself accomplish the task without changing it... 
• Also pay attention to the space around you, to the sounds and odours as you carry out the activity. Gradually increase the range of your consciousness, encompassing everything that takes place during the activity.