My personal rule for playing in dropped D is to avoid the 6th (bass) string when making any chords that the extra two frets would make hard to reach. For example I make the "F" chord in the "beginner way". Index finger across first fret of "treble E" and "B" strings, middle finger on 2nd fret of "G" string, and ring finger on 3rd fret of "D" string. I just don't try to get the lower notes of the chord.

I also tend to only play in the key of "D" when I use dropped "D" tuning.

I think it is a great tuning. It has many of the advantages of "standard" tuning, but does give a richer bass.

If you drop the treble "E" to "D" also, you can play "knife songs" in the key of "D" by alternating between the 6th and 4th (or 6th and 5th, etc.) string with the thumb and sliding the knife along the first string for the melody.

Murray