First-season spending tends to go to the wrong places. Owners furnish for photographs and then discover that guests judge a house on the things that do not appear in any of them.
Spend on beds, mattresses and blackout in the bedrooms; on hot water that copes with the full occupancy; on outdoor seating that matches the number the house sleeps; and on a kitchen with sharp knives, enough pans and a decent coffee method. These are the things reviews are actually made of.
Hold back on decorative renovation, anything fragile, and specialist equipment nobody asked for. Buy commercial-weight linen in a single colour so replacements always match, and keep a spare set of everything. Then photograph the house properly once it is finished, in daylight, with the beds made.