How do I consistently gain in forex, gold, futures, spot, option? Among those mentioned above , which is the fastest and safest to invest in? Is there any guidebook or forum for us to learn or interact each other relate those investment skills?

Financial instruments such as forex, gold, futures, spot, option etc are considered many to be risky, especially if you do not know what you are doing. For example, driving a car is dangerous unless you make the effort to learn how to drive safely. Likewise, trading in financial instruments is risky unless you make the effort to learn how to trade the instruments safely.

Sorry, my private point of view:

these are exactly asset classes that the retail investor surely should avoid given they are highest risk and often short term trading instruments, when even finance professionals cannot predict the price developments