The zero-cost collar is the classic setup: choose strikes so the call premium equals the put premium, eliminating cash outlay. Result: you give up upside above the call strike in exchange for free downside protection below the put strike. Useful for concentrated positions you want to hold through volatility without paying for hedging.
Variants: the credit collar (call premium exceeds put premium, generating income but giving up more upside) and the debit collar (more put protection bought than call premium received, costing money but tighter downside cap). Choose the variant based on your conviction and downside tolerance — there's no single correct collar, only one that fits the position's risk profile.