These need to be looked at with great care, the practical approach will be some or all of:
Giving assets away while alive, be it to friends, family, charities and trust planning. However in disposing of assets by gift there may be immediate Capital Gains Tax implications. Also Trusts need to be treated with more care than most people think (use the wrong one and its internal tax rate may cancel out any apparent IHT savings). Advice and planning is essential.
Plan to meet the IHT liability through life insurance. A life insurance policy which pays out a sum equivalent to the estimated liability is taken out and placed into a trust meaning it falls outside the estate.