The cross step is part of the art, controlling the speed of the board as you walk forward and stand with nothing but water in front of you...it's the best feeling. Walking back can be a blast too. When that split second decision is made to walk back, the board may often speed up and that acceleration can throw you backwards, hands thrown in the air to balance.
If I was to give one piece of advice bearing in mind I'm no expert just a lifelong student myself...take one step forward, one back. Repeat this like 'The Way of the Samurai' over and over and over. When your comfortable...take a step forward, then another...you might find you've landed on the nose.....and NEVER..EVER shuffle!