What is the best way to buy THETA?

Inquiring minds want to know: What is the most effective strategy for acquiring THETA tokens? With the cryptocurrency market fluctuating daily, it's crucial to approach investments with a calculated and informed approach. Could you elaborate on the optimal methods to buy THETA, considering factors such as exchange selection, transaction fees, security measures, and the potential for long-term gains? Your insights could be invaluable for those looking to enter or expand their presence in the THETA ecosystem.