So much depends on your attitude to risk - as has been said the safest way is to container the thing across...
It was a while ago now when I did it so the rules and regs/ airspace requirements may have changed a little since.
1. Equipment - can be hired from Far North at Wick. It can be a one way run dropped at Goose or held back for the return trip. Dingy and survival suits at the very least, “wet bag” and rations at your discretion. You may want to do a sea survival course which may help some.
2. Routing - depending upon the time of year (Winter is not the time to do it!) you can do the traditional Scotland - Reykjavik- Narsarsuaq - Goose and on or the slight more northerly “Blue Spruce” route where the legs are slights shorter but the overall distance much longer. The MSA in southern Greenland is 13000’ so you might want to factor that in..,
3. Tanking - the only time you can have too much fuel is when you’re on fire. The actual need to tank can be done away with by flying the blue spruce but you’d need to make sure all your planned stops have fuel available for you. If you tank- get the proper paperwork. CBP at Bangor we’re all over us for our 337.
4. Chstoms / Immigration / Visas. If you’re heading into the US you will need a visa as the visa waiver programme is not applicable. Greenland weren’t interested - “this is Greenland, you can stay if you want!” Was the response when asked if they wanted to see passports etc.
5. Radio - no real need for HF as you can stay below class A but bear in mind comms range with the terrain is very limited. Satphone could come in handy but is not a legal method of comms.
6. Diversion options are very limited so plan carefully and always give yourself an escape route... even if that is a 180.
That’s about all I can think of for a quick response....