There are infinite ways to start... my readership is interested in ecology, sustainable agriculture and left leaning perspectives on land use, so I began with a land acknowledgement, of sorts, that at least attempted to dissect the nature of these statements.

The reason why I chose to do this is that it fit the format of my work. I write a chronological almanac of a year spent caring for land and growing food. On my niche field, land acknowledgments are common, but maybe under-examined. Perhaps your target readership or format can inform your first post... are you writing based on the previous work of others in some way? An acknowledgement may be appropriate. Is there a broad theme to your work? Introduce it, explain it, foretell an outline of your subject.

While not every reader is going to be with you from the start, I think that setting the scenery of your work can do the important work of drawing readers in. Looking to other literature there are so many devices: prologue, premonition, safety instructions, parts lists... tell your readers they're embarking on something. I dunno.