The best estimation tactic I've found in practice is ROPE, which works because it helps different kinds of stakeholders understand different kinds of estimates and ranges.
R = Realistic estimate. Based on work being typical, reasonable, plausible, and usual.
O = Optimistic estimate. Based on work turning out to be notably easy, or fast, or lucky.
P = Pessimistic estimate. Based on work turning out to be notably hard, or slow, or unlucky.
E = Equilibristic estimate. Based on 50% probability suitable for critical chains and simulations.