Standard 440 tunig will work. E A D G B E
I prefer tuning all strings down 1/2 step to E flat.
If you play slide then you would need an open tuning like D A D G B D
Standard EADGBE is usual. For playing solo in D, dropping the low E to D is common. Slide is fine in standard tuning, too, although open tunings are also used by some players.
Standard tuning works in most situations.
If he is unfamilar with standard tuning he should take lessons.
Slide players however tune differently in different arrangements.
Your brother should pick up GuitarPro5
Low to high for standard tuning is EADGBE. Open tunings can be tuned to open E chord or D or others.
Standard 440 tunig will work. E A D G B E
I prefer tuning all strings down 1/2 step to E flat.
If you play slide then you would need an open tuning like D A D G B D
open g is common, but standard eadgba tuning is also used.
open g is dgdgbd.. only the first two and last string change and they make the same tune as a g major chord when strummed
Standard EADGBE is usual. For playing solo in D, dropping the low E to D is common. Slide is fine in standard tuning, too, although open tunings are also used by some players.