Ok, then here are my suggestions in regards to mobility/flexibility:
1) Perform primarily dynamic stretches pre-workout. Dynamic stretches are those which move the body through it's range of motion without passing for extended periods in any one position (if you want to hold the stretch for a second or two that would be ok). Dynamic stretches can also be "passive" (meaning either gravity or some external resistance is pulling your muscles into an eccentric stretched position and then you are contracting them to pull yourself out of the stretch), or "active" meaning that you are contracting one muscle to pull it's opposing muscle/antagonist into a stretched position) in nature. I will often incorporate some passive and some active dynamic stretches into my warm-ups depending on how I feel and how tight a muscle/range of motion feels.
If you are going to perform static passive stretches, then Inwould recommend you only perform them on muscle groups that will not be called on to produce high amounts of force (either dynamically or statically) during your subsequent workout/class. For instance, it would generally be ok to perform a static chest stretch in order to facilitate a better "rack" position prior to performing back squats as chest flexibility may limit squatting performance, but the chest won't be called on to produce high amounts of force during the squat.
2) Introduce mobility/dynamic flexibility exercises into your workout itself by placing them between sets of your strength training exercises. This increases time management as instead of just sitting around watching the clock tick between sets as many people do you will instead be using that "wasted" time to perform flexibility/mobility exercises. This tends to also increase the other all cardiovascular/conditioning effect of your workouts, keeps you warm, and keeps you focused.
I generally prefer pairing your strength training exercises with mobility exercises that target the antagonists of your exercise or at least the limiting muscles. For instance I might pair squats with an ankle/Soleus mobility exercise as many people's performance of squats is limited/hindered by lack of ankle mobility. Or I might pair a rowing exercise with a mobility exercise for the chest as a tight chest will inhibit full contraction of the scapular retractors and shoulder extensors/horizontal abductors.
3) Perform a dedicated flexibility workout for at least your upper body and one for your lower body (you can split the lower body up into a hip flexion/hip extension [sagital plane) session and one for hip abduction/hip adduction [frontal plane] if you want) once a week. During these workouts you will want to hold the stretches for much more extended times (1 minute to 2 minutes) and try to work towards your maximal (moderately uncomfortable, you should never feel sharp pain while stretching) range of motion for that day. That generally means going to the point of feeling tightness in the muscle (the stretch/myotatic reflex), waiting in that position until the stretch sensation decreases, then "taking up the slack" until you feel another stretch sensation and continuing in this process until time is up.
4) Be consistent (consistency is more important than intensity IME), don't push too hard that you risk injuring yourself, and be patient. Flexibility takes time to develop, just as strength or endurance do, so focus on performing your stretching/mobility exercises to the best of your ability and let the "outcome/long term" goals come in their own time. This outlook (which honestly can be applied to all areas of training) will provide for a much more pleasant and rewarding "ride/journey" then always focusing on the finish line.
Hope this helps.