Having the queen marked, transforms manipulation and is well worth the
effort.

Finding queens is self reinforcing - very difficult the first time but
gets easier the more often you have success. For sure it is easier early
on in the year when there are less bees and they are less aggressive.
I find the following method useful :
 Withdraw the frame and immediately start looking at the side which was
next to the other frames (the dark side)
 Quickly look around the Periphery then more slowly look along the frame
in roughly 2.5cm (1") strips, sweeping down strip by strip until the
whole frame is covered .
You can practice this on an A4 sheet of print onto which someone else
has put an "out of position" full stop(period) This "moving strip"
method is useful for finding any small object (such as that dropped
screw from your spectacles which has landed on the heavily patterned
carpet)

If possible for the first time or two, it is useful if an experienced
beekeeper can locate the frame with the queen on and hand it to you only
with the information that the queen is on there somewhere. Once you have
achieved it 2 or 3 times it will seem relatively straightforward (in a
not too crowded Colony) Later on in the year with colonies "boiling
over", finding the queen can be quite a challenge even for an
experienced beekeeper.

Using a Queen excluder to "riddle out" the queen is very stressful on
the colony (and the beekeeper) and should only be carried out in
emergency.

Alan Riach