I mean I totally agree with the that. Bach is a genius, on a very deep level.

But if OP is asking for some basic tricks to make something sound more baroque like - maybe in the context of an advertisement spot or something humoruous - then I guess there are some, like learning the 4 cadences (soprano, alto, tenor, bass) and just writing them on top of each others. Or some kind of melodic arpeggio structure or basic chord progressions, circle of fifths with seventh chords + resolutions....

The following comes from personal experience and not from any academic or professional authority:

That is somewhat of a misconception or perhaps a misinterpretation of his music. What signifies Bachs music isn't trills, ornaments and turns. Rather it is signifies by the appropriate and, dare i say, correct usage of compositional tools in the appropriate context. Simply including the aforementioned forms of melodic flourishes won't make it Bach-like. To do so you must create a coherent musical context with appropriate movement with respect to the harmony which in turn should remind the listener and player of  Bachs music. 

Again I'm only an expert in the sense that i have listened to the majority of his works. What I'm saying here is a personal opinion/interpretation of my experience with Bach.

He was a genius in harmonic modulations and secondary dominants. The last part of an opening theme could simultaneously be apart of the beginning of the next phrase/response or exposition. You’d have to be familiar with counterpoint as well as Bach style of harmony, as well as augmentation, diminution, retrograde and inversion of phrases, then indirect and direct modulations, the Picardy third, and rate of harmonic change, like every half or third of one bar. A lot of composition students like to compose modern pop songs as baroque counterpoint pieces on YouTube, but to make it Bach like, you’d have to be really familiar with his music or really know what’s going on in his music. A book a lot of composers used was Gradus ad Parnassum by Johann Joseph Fux. That could be a start, or just listening to Bach if you have a good ear.

I wouldn't say fux book is a waste of time. It gives you valuable insight into how counterpoint is taught at the time despite it isn't an exact guide to sounding like Bach.

Older treatises can be helpful if you are willing to spend the time studying them, but they aren't the go to books for developing your own composition methods. Your own method is best developed through studying existing music since the music itself aren't a product of the guides. The guides are generalizations describing how music is made at the time. They are just generalizations while the music pieces themselves provide the necessary materials for your own analysis and research

Clichés? Well...harmony using circle of fifths and descending by thirds, suspensions, imitation in general (and fugal techniques by extension), the use of ritornello (in concerto & dance movements, arias, choruses etc.), melodic development using fortspinnung, and so on.

But unless you already know and use these in your writing, it will probably just sound like an incomprehensible word salad. Get a hold of the basics of composition - its usefulness will extend far beyond just trying to write Bachian pieces. Learn about functional harmony, voice leading, and melody writing. Then study chorales and a little bit of 18th-century counterpoint, and you'll be good to go. **Do not bother with Fux's Gradus.** It is a waste of your time since it exclusively deals with 16th-century counterpoint (and only partially succeeds at doing that).

You can try to use imitation (see c major invention), even if it won't sound great immediately, you will probably get a Bach-like effect on the surface, if the audience isn't very educated musically

Hey guys, I’m currently in the midst of composing a Bach-style piece. So I need help. What are some common clichés Bach used other than lots of turns and accidentals?

Help!