Matt,
I'm not a fan of Solid Wood tops but am often asked this question.
Treat with the oil recommended by the manufacturer and apply 4-5 coats allowing to dry before installation. End grain sealer should be applied to finished ends
Allow 5mm clearance where the wood meets an elevation.
When fixing from the underside use oversize angle brackets and fit washers to the fixing screws and don't overtighten so as to allow movement
Use aluminium foil on the underside of the tops above dishwashers and any other moisture creating appliances.
When cutting use a circular saw and cut slightly oversize so that a neat finish can then be achieved with a router. Use quality tools and blades for the purpose.
Make joints using a good quality silicone sealant, again to allow movement of the wood. Ensure you remove all traces of the silicone as it will otherwise stain the top.
Finally, consider ditching the idea of fitting Solid Wood and installing Quartz or Corian worksurfaces.
Good luck
Tim