The major insurance lines have vastly different goals, headaches, nuances and focus, so a policy admin replacement project will differ by business line. But end goals always are the key to the game. Know your business objectives.
Conversion is the 500-pound gorilla that no one wishes to tackle, but it must be tamed earlier than most would imagine. And don't start mapping and fixing piecemeal, as you will be there forever. Assess the data and work out the level of effort to cleanse before you start the process of PAS replacement. Then set your plan accordingly and gain executive buy-in.
Selecting the right vendor and product is a crucial step. If you back the wrong technology, it will be much harder (and more expensive) to meet business expectations, even if project management practices are first-rate. Shortcutting the selection process may save a few weeks up-front, but it will add many months and dollars to the overall implementation. External market expertise can help distill true product capability from marketing hyperbole.
There is no substitute for battle-hardened project and vendor management skills. PAS replacements are not the best projects for a PM to learn the ropes. Be realistic about internal capabilities and hire if there is a skills gap.