Get your procurement template correct. Be realistic about costs as HR/payroll systems are not always as cheap as you think they are. Be very vigilant in your PID or FNFR documentation to ensure the supplier is aware of all of your requirements, including any complex reports. Make sure you cover costs for training. Spend time planning before just rushing out to buy this product. Get NGA to give you a realistic demo rather than the glossy sales pitch, and finally, make sure you have a consistent PM. We went through 4 PMs in the end and there was no joining up so you find yourself repeating everything, and nothing gets resolved quickly. Ensure you have regular contact and meetings between your company and NGA.