In order to create a sustainable retirement plan, you're going to want to balance growth with protection. Precious metals can help with that, providing you with an asset that usually responds differently than stocks and bonds in stressful times. You are not looking for large wins, but instead trying to smooth out the ride and protect your purchasing power. The biggest factor is how large you make your allocation, what vehicles you utilize, and managing the details with some reasonable discipline.
Understand what gold IRA is: https://en.wikipedia.org/wiki/Gold_IRA
How much allocation is reasonable?
There is no magic number — goals, risk tolerance, and time frame differ widely. Many planners "test" small allocations first, and adjust as they see the effect that metals have on the swings in their portfolios. Think of your rationale for metals — either inflation hedge, crisis insurance, or just pure diversification — and then pick a reasonable range based on that rationale.
Common starting allocations in diversified plans are 2–10% combined in gold and silver.
If you are looking for more "crisis ballast", you will be testing the higher end. Conversely, if you are very growth-focused in your strategy, you'll be looking to remain closer to the lower end.
You also have the availability of using a self-directed IRA for tax deferred precious metals exposure or holding a portion of your allocation in liquid ETFs for relative ease of rebalance.
Regardless of which IRA provider you decide to work with — which could include providers like Goldco — always compare custodian fees, storage fees, and the buy-sell spans prior to funding.
Core-Satellite Portfolio Approach
One possible framework to think about metals in your retirement portfolio might be to maintain your core (broad stock and bond market funds) and metals in your satellite allocation. The core ultimately performs the heavy lifting (to the long-term growth). The satellite portfolio with metals can reduce drawdowns and diversify returns. You can combine your modes of delivery; you could keep physical bullion stored in an approved IRS precious metals depository for permanence and then have the small sleeve of ETF metals for liquidity.
In your interest to personally hold metals in your retirement accounts, you must utilize custodians and depositories, not home storage.

Risk-adjusted return introduction.
Metals do not necessarily always "go up", but they typically zig when equities zag. Value stems from metals correlation and how they can create an influence on the journey of total returns. In order to think through that potential influence, think in terms of portfolio metrics, not metal prices.
Sharpe and Sortino Ratios: do metals increase return per total or downside unit risk?
Maximum Drawdown: does gold or silver lower your highest peak to trough loss?
Rolling Correlation: how do metals move with equities and Treasuries through different regimes?
Stress-test years: potential crisis years in which metals may have proved useful on down markets and inflation spikes.
Liquidity and storage considerations.
In general you have three options: physical coins/bars, metal backed ETFs, and IRA compliant holdings through custodians. Owning a physical bullion grants you title to ownership of the physical metal, but comes with a premium+shipping/insurance. ETFs are a transparent approach to trading and rebalancing but carry fund provider and fund structure risk. When using a gold/silver IRA, remember that your gold/silver must remain in the IRS approved depository and checklist and be advised as to where the approved locations are, fees, filing/reporting, how to manage Required Minimum Distributions (RMDs).
If you are using a company like Goldco for your precious metals IRA, request a standard fee schedule and a sample trade ticket. Ask how they source authorized coins from the IRS, settle transactions, and quote spreads on purchases and sales. For all direct purchases outside of retirement accounts, retain invoices of your transactions and purity forms to organize and track for future tax records down to the ounce. Clean receipts and documentation make tracking cost basis and any possible capital gains reporting easier.
Triggers for Rebalance and Frequency
Adding metals is step one, keeping the allocation in range is step two. Rebalancing encourages buy low, and sell high behavior, and stops the satellite from going too far below or above its target. Make your rule before the markets get noisy so you do not act emotionally.
Calendar: quarterly or semiannually. If you need to revamp, keep your allocation near its target.
Bands: take action when and only when metals move outside a ±20% band of the target size (e.g. trade at 6% target, hold at 7.2% or 4.8%).
Cash flows first: use contributions or withdrawals to move your allocation without triggering other taxed events.
IRA specifics: in a Goldco or similar self-directed IRA, be aware of the times to settle, if you need to sell or buy and get to your rebalance. Learn more on how gold IRA works.

Practical Implementation Considerations
Start small and experiment, with a paper plan or a small allocation. Have all your options on the same shore: physical, in a depository, for the protection; ETFs for the liquidity; and an IRA sleeve for the tax deferral. While doing so, keep notice of your total cost of ownership, as many of the things that go along with your metals, custodian fees, storage, and transaction spreads, are just as important as what you see in terms of headline spot price. Remember to document your thought process and thresholds so your future self knows why the allocation is there.
Additionally, when rolling over or transferring funds into a metals IRA, be mindful if it is a trustee-to-trustee transfer, so as not to fall prey to the 60-day rollover trap. Also, confirm the coins and bars you have created meet IRS standards for purity and eligibility. If using a provider like Goldco, ask for sample confirmations showing, metal type, weight, intentional fineness, and storage location. Your records assist with audits, insurance, and eventual distributions.
Bottom line
Precious metals can be used as a satellite holding that stabilizes risk and provides diversification to your retirement portfolio. Establish a purpose and an allocation that reflects that purpose, and select vehicles that match your liquidity or permanence needs. The details—storage, fees, and rebalancing—become manageable, and your allocation will do its job ceremoniously behind the scenes. Using thoughtful process and due diligence on your provider, your metals sleeve becomes a long-term portfolio tool, instead of a bet on what-the-next-headline-might-be.