Buyers with complex risks should start preparing at least six months before their renewal date, according to Marsh, the UK's second largest broker.
This is part of the advice to be given to insurance buyers at a seminar on how to cope after the hardest renewal season in decades.
Marsh is holding the Manchester seminar to help buyers cope with a range of difficulties.
In addition to soaring premiums, buyers have been facing demands for almost unprecedented amounts of information before insurers will sell cover.
Marsh managing director Peter Leahy, the practice leader in risk management for northern UK, said
He said: "Insurers and reinsurers are having to concentrate on their aggregate exposures in a way they haven't done for many years.
"They are requiring much more detailed information. Because there is an overall reduction in capacity, buyers are having to talk to insurers they haven't dealt with before and who aren't familiar with their risks.
"This all means the renewal season is very long and detailed."
Marsh's market view and advice, will include recommendations that buyers:
The seminar on 7 March is at Bridgewater Hall. It will give a legal overview of current claims and will look at management strategies to keep costs down.
Leahy said some clients had seen premiums increase by up to several hundred per cent for property risks.
