I don't know that I'd avoid the partitas or the suites -- Bach's music is polyphonic even when he's not writing fugues. And I find that the fugues are devils to play, and not necessarily easier than, say, the Bb Partita or the Italian Concerto.
From the WTC book 1, I would mention that the 4 voice fugues can be nightmares to arrange and get under your fingers. You are probably aware that the odd-numbered ones are in major keys, the even numbered ones in minor.
Number one in C major has an easy prelude, if you can resist the temptation to flood it with pedal. DON'T use pedal at all in any of Bach. The fugue, however is a 4-voicer, and not too easy.
I would look at #5 in F -- even though the fugue is 4 voice, it is pretty easy.
#2 in c minor is famous, with a really nicely arranged fugue that fits well under the fingers
The 7th in Eb has the most gorgeous prelude, and the fugue has sone absolutely incredible sequences in it -- but it's not an easy one.
These are just for starters.
Try to stay away from extremes in dynamicx. Bach writes the "dynamics" into the music by thickening the texture, the vertical density (more notes per beat), and the horizontal density (more voices). Crescendos and decrescendos are really not in the style. Rubato and big tempo changes are not in style -- keep a steady beat.
Bring out the fugue subjects when they appear in each voice -- not so much with dynamics but with articulation -- remember these were written for harpsichord, and Baroque articulation had to do with the note values involved. In general, 16th note runs are played legato, and the note longer values note values (8ths in this case) that are in juxtaposition should be played non-legato (with just a bit of space between notes). Leaps are generally played non legato, stepwise passages legato. There are whole books written on the finer points of Baroque articulation, so what I have given you here is incomplete -- and there are ALWAYS exceptions to every "rule".
Listen a lot to other good baroque players. Glen Gould's Bach playing is considered by many to be THE way to play Bach on the piano. I find him a little dry, and I question his tempos -- but he plays the pieces with astounding clarity and evenness. I would try to emulate that aspect of his playing.
There are others in this forum who will have much of value to add, and will disagree with me on certain things -- listen to them.
Cheers
Glinzek