To calculate the trade size you must measure the potential risk against your available funds. So once you have identified a stock, the next step is to calculate the Reward: Risk ratio using your stop loss and a realistic target price. Your trade show booth manufacture Reward: Risk ratio should be 3:1 or greater. The Reward is worked out by your target price minus the entry price, the Risk is worked out by entry price minus where you have put your stop loss.
Continue this process until all the air has escaped