I haven't started an a priori
lang from scratch in at least 20 years (prolly more).
I would just start writing or recording some phrases that would be how it would sound.
Usually it would be as part of a prayer, or a reaction to an image I liked, or part of a song I knew, where I'd just start
singing along 'in tongues'.
Then, I would break down the utterance as best as I could into words/moræ.
I'd analyze it according to the context, figuring out word classes.
After a few trials, I'd start looking at the resultant words. Do they look like they have any affixes (especially ones that repeated in other words).
A little bit further, I start generating plasmodia of related concepts. Aggregations of related terms.
In an utterance that included words for "mom" and "dad", what might 'grandparent' look like? What might 'aunt' or 'uncle'?
In a lyric "good or bad, happy or sad", what might be some adjectives for 'good sounding' i.e. 'mellifluous', 'harmonious', 'good smelling' i.e. 'fragrant', 'aromatic'. What would their opposites look like?
Pretty soon, I'll have
whole nest of vipers
entire breeding rookeries of nouns, verbs, ADJs, PRPs, CNJs, etc.
The actual phonology and orthography comes from creation-use-redaction-creation-use-redaction…
I don't think I ever started a
lang by just beginning with the way sounds are created.
I suppose that's useful, but to me, only in so much as it helps finalize the sound of the language, and help weed out
spurious phonemes or phoneme combinations.
I do not use wheat-paste or cellophane tape in the creation of my conlangs (anymore).
Still, I guess I'm one of the elder-fashioned
langers in the bunch.
I imagine, nowadays, I might put my years of linguistic grad school more to use in the process.
My process might look more like OTʜᴇB's flow-chart, which is impressive, and not the least daunting.
Anymore, I don't think I have the gobs of free time to build that way. But more power to those who do!