We usually accept TT in advance or irrevocable Letter of Credit at sight. For total order value under 10,000USD, it is better to choose 100% TT in advance as the bank charges is high if arrange the payment twice. For total order value over 10,000USD, we can accept 30% TT in advance and balance before shipment. While for total order value reach 30,000USD, we can accept irrevocable Letter of Credit at sight, but we do not advise you to choose L/C the handling costs is high, so we also suggest you to choose TT as it is safe and fast.