The reading order for the Solstice Dragon World series is a personal choice since they are standalone novels.
But… there are options:
Start with Book 1, The Dragon Question, and read to the last current book. (series order)
Follow The Dragon Question story: Book 1 then Book 5.
Follow Rasmuth’s story: Book 1 then 3 then 5 then 8 (possibly 10, still planning that one).
Follow Codger’s story: Book 1 then 5 then 9 currently on pre-order.
Follow Brundar’s story: Prequel (The Don’t Eat Humans Clause) then Book 3.
What not to do if you prefer to avoid spoilers:
Best not read Book 5 before reading Book 1.
Best not read Book 8 before reading Book 5.
NOTE: Reading Book 2, Dragon Bone Ridge, first creates no problems at all.