Even if you avoid DIY like the plague, there's still a basic toolbox that you can't survive without:
By a mysterious process, most people end up with a dozen screwdrivers rolling around the backs of drawers. A four-in-one, with two sizes each of flathead and Philips drives, will make most of the others redundant.
Works much better than a stone, or the heel of your shoe, for hitting things. With a claw hammer you can also lever out nails - works much better than your teeth.
If you don't have one of these knives with sharp, retractable blades, you'll end up ruining a kitchen knife and getting really annoyed.
As well as gripping, pliers will also cut wires. NB: If you don't know your live from your neutral, better not go cutting any wires.
Get one that's long enough - at least five metres - and not just metric. Imperial measurements haven't gone away, you know.
A straight edge with a bubble in a glass vial and you must keep the bubble between the lines. That's unless crooked shelves don't bother you, in which case just do it by eye.
Drill and drill bits
A good drill - electric, cordless or hand-powered - is not the whole story. You have to use the right bit - wood, masonry or metal. Not suitable for DIY dentistry.
On acquiring your first basic carpentry saw, you will learn - probably too late - the first rule of carpentry: measure twice and cut once, not the other way around.
One of the most versatile 20th-century inventions in the field of hand tools. A lockable grip that can be a spanner, pliers, clamp, or even an emergency handle.
WD40 and duct tape
Not tools, but the dynamic duo of emergency repair. The motto is, if it doesn't move and it should, WD40; if it shouldn't move and it does, duct tape.