Using glue or toothpicks will just result in a loose joint and the
thing falling apart again in the near future.  Also, never be tempted
to drill oversize and fit a piece of dowel.

The correct way is rather time consuming but you will never have a
problem again.  For each hole you need to remove all parent wood around
the hole to the depth of the screw.  The diameter will depend on the
gauge of screw and the availability of a plug cutter.  I have two
sizes, 3/8-inch and 1/2-inch.

Drill the hole, centred on the screw hole, to the diameter equal to the
plug cutter.  Cut plugs in a piece of identical wood from your wood
store, with the grain running across the plug, and glue into the hole,
pushing right down to the bottom.  You may need to 'piggy back' more
than one plug if the hole is deeper than the length of a plug.

Ensure that you position the plug grain in line with the parent wood
grain.  The top of the plug will sit proud, so simply plane it flat.
Redrill the correct size for your screw and fit.

The resulting job will be as strong as new and you will hardly see the
join.  Toothpicks, glue filled holes, fibre plugs and end grain dowel
are the signs bad workmanship.  Don't do it!

Nicholas Simons, GB