G'day Vaivara,
While giving advice to someone I said, 'I don't know how deep and far you want to go...'
This sounds a bit redundant as deep and far basically mean the same under these circumstances.
How about;
While giving advice to someone I said, 'I don't know how deep you want to go...'
While giving advice to someone I said, 'I don't know how far you want to go...'
While giving advice to someone I said, 'I don't know the depths you want to go...'
While giving advice to someone I said, 'I don't know to what depth you want to go...'
Stannum