Site details - know what you are planting in to Rainfall and other climatic factors. Collect these from a reliable source, and check the range of values. If you haven't been to a soils workshop, get advice from a local resource assessment group. Quite important in windbreak design and nature conservation. Size and growth rate Site requirements and tolerances Climatic.
Rainfall needs, frost tolerance, drought tolerance etc.
You may need local interpretation of some of these factors - waterlogging and inundation commonly misinterpreted. Check against local disease knowledge. Phytophthora and Armillaria are common in the south west. Local experience is necessary about pressure from insects and other pests attacking particular species. Problems Weed status.