...
Any tips going from 1st to 2nd and avoiding a jumpy take off?
Practice, my friend.
Often times newer riders as well as "so called experienced riders" are overconfident about their riding skills, and think they can ride better than they really can. By the same token, some riders are just the opposite, under-rating their riding skills. In both cases, this can be a great danger to both the rider, and often to those around them. It may not always be easy, but all riders must be real about their riding skills. Being confident in yourself and your bike is the key to being a good, safe rider. So being over or under confident can be a problem.
Often times, riders will ride fast, thinking they are showing their skill but this is rarely the case. Riding at very low speeds takes much more skill than riding at higher speeds in a straight line any day. With even modest skill almost anyone can lean a bike far enough in a slow-speed turn to drag a peg just as well as someone can drag race a custom street bike. The one common thread that is relative to both riders is that, for them to get to that particular level of confidence, there was practice involved.
Practice in order to get better at what is difficult - to become skillful. Practice increases confidence. Confidence shows as 'skill.' Schedule some time to practice away from traffic. Consistently practice your skills and improve yourself as a rider. This helps you in knowing the dynamics, effects, mechanics and limits of you and your bike.
Just remember a good mindset and concentration are of utmost importance when riding. Before you get on the bike and turn the key, take a minute to relax and focus, it could save your life.