Preparing for ILR

The only definitive info is complete the online questioning
https://www.gov.uk/settle-in-the-uk

then commence an online application until you get to the part where it lists documents required.

If your circumstances haven't changed since previous FLR application, then its simular evidence (Finance and addressed correspondance covering last 2 years), with the need to have now done the life in the UK test AND meet higher minimal english language grade of B1.