Methods for starting and operating ionic liquid catalyzed hydrocarbon conversion processes and systems to provide maximum process efficiency, system reliability and equipment longevity may include: purging air and free water from at least a portion of the system; introducing at least one reactant into the at least a portion of the system; and re-circulating the at least one reactant through the at least a portion of the system, via at least one feed dryer unit, until the at least one reactant exiting the at least a portion of the system has a water content at or below a threshold value, prior to the introduction of an ionic liquid catalyst and/or additional reactant(s) and feeds into the system.