These ideas are not "rules". This period included great diversity in all aspects of music making. There are certainly exceptions every idea here. These are general observations: a place to start.
For virtually all instruments, the history of the development of old instruments into new instruments involves the increase of power range, and facility, at the expense of color. The seeking of lost color is a fundamental goal for HIP instrumentalists.
Composers in the 17th and 18th centuries put much less information in their scores. An early piece is likely to have only notes and perhaps a title and tempo: very few dynamics, articulation, bowings, fingerings, accents, and other expression marks. This means that there is much more responsibility for the player to make interpretive decisions if the music is to come to life.
In general USE the meter given, meter should be clear, and the bar lines should actually be heard. Articulation, emphasis, note length, and even rubato can be used to bring this to life. Metrical clarity and and audible bar lines are VERY important to the interest of this music. (And incorrect for much later music)
If you have doubts (4/4 or cut time? say) then gauge the tempo so that both work.
Most period instruments are softer than modern counterparts, and most developments in instrument involved increasing power (at the expense of color) so it is safe to assume that period players tried to get as big a sound as they could.
Most of the writer/teachers of the period put great emphasis on interesting dynamic shapes in longer notes. Quantz writes about stressing dissonances.
It is however quite useful to remember that in general individual baroque movements are "about" the expression of a single affection or passion. (long unwinding phrases of similar material "fortspinnung") This is distinctively different to the classical (sonata allegro) structure which is specifically "about" the dynamic contrast of several different passions or emotions (primary and secondary themes and many short contrasting phrases)
Music of this period has earned a very unfortunate reputation as mechanical. ("motor rhythm, sewing machine music", etc.) It should instead be viewed as a highly emotional and expressive period. Fast music is usually based in dance, and slow music is based on highly expressive vocal models.
Remember the idea that each movement was intended to be the expression and expansion of a single affect or emotion. If a performer or ensemble will decide as specifically as possible what affect it wishes to portray and intensify in a movement it then has a consisitent and coherent basis for making further decisions on tempo articulation, dynamics, and the like.
Making the meter and rhythm structure very clear (bar lines audible), and stressing the proper notes (inegales <---> swing) enlivens the music a great deal. Ornamentation is quite enlivening.
Bach, Telemann, Couperin and many many others wrote ornament charts. Telemann Quartz and Tartini wrote specific examples of ornamented movements. Bach's "doubles" in the suites are superb examples.
I suggest the following exercise: take a simple slow movement: play it through adding trills every place you can manage. Some will sound good and others will not. Learn from that. Repeat the movement, this time with mordents all over the place. Learn. Then appogiaturas.... and so forth.
Be aware as you do this that you are developing both your skill in performing ornaments and in choosing when to add them. You are also dealing with issues of taste. It is very very easy to add too much and end up with ornamentation that is boring, tiresome, showoff and shallow.
After doing this with all the ornaments you know, go back and repeat the movement, and only put in the ones you really liked.
My own opinion is that the highest form of ornamentation takes places when 2 or more players embellish live, and interact ornamentally with each other, yet tastefully not so much that the original music is obscured. I fancy that this is an informed opinion.
There are numerous references that vibrato is an ornament and therefore NOT used all the time. There is also great disagreement (Geminiani and Tartini) about whether to use vibrato on mezza da voce (long shaped notes). I suggest practicing some of the time COMPLETELY without to develop more deliberateness of vibrato as an ornament. A somewhat narrower than usual vibrato can help produce an clear and transparent tone in which all parts can be clear.