The key card is present but its support is thin.
Prioritize useful support such as Guidelight Optimizer or Camera Launcher.
Establish Rangers' Aetherhive or Rangers' Refueler before activating Skyserpent Seeker. The payoff trigger resolves before exhaust, then the Seeker supplies two tapped lands for future activations.
Your deck enables the plan but is losing the early turns.
Take a castable early creature or efficient answer before another expensive payoff.
Guidelight Optimizer's mana is restricted to artifacts or abilities, and Skyserpent Seeker's lands arrive tapped. Neither promises immediate unrestricted mana for every spell in your hand.
The support is missing
Favor independently useful creatures and interaction if the narrow support does not arrive.