Hard to give you an immediately applicable advice, it was very, very long time ago. Some points though:
-- try to observe him and determine what his interests are, at least on a very high level. Is he attracted by mechanisms? electronics? architecture? sewing? something else? In my case, it was easy, I started to break toys since I started having them, my parents reprimanded me until they noticed that I don't actually break them but dismount properly. (For that, obviously the toys had to be of the kind allowing that, not all in one piece.)
-- the workshop doesn't have to be big, but
a) it should allow instant access to any tool of the collection, any time. Storing them in a locked box hidden away and taking out for the occasion won't work.
b) you need to have a full set of tools allowing to start and complete a simple operation (and safely at that), i.e., to be able to saw the piece, it needs to be firmly attached, etc. To control the investment, optimize on the number and type of of operations -- think of making something very simple, make sure the child shares your interests, and equip for that, but from as to z. (To illustrate -- a bird's house requires a saw, a hammer and couple of nails, but make sure the child cares about birds getting it.)
c) tools don't have to be expensive and complicated, but they need to be above junk quality. If you yourself have the experience, you should be able to determine the required minimum. If not, ask a friend who has. Some of them simply cannot be of "kid version" (drills, for example), don't buy that. In my case, it was the time when tools were inherited from father to son, and none of them were electrical, but all of them were good, I just had to learn to use them -- at the beginning, this will test the kid's patience, so dose carefully. (At the same time, this is where the bulk of the skill development lies, and the age is right too, so...)
d) try to teach your kid to clean up the mess after they finished for the day, but don't set out with high expectations ... sometimes, they will be just too tired after having fully invested themselves in the process fro several hours.
e) help him to always reach the end of each project, not just drop it because they lost interest. But do not insist. This is the hardest, much harder than d).