Yuttadhammo is correct. It is better to bias yourself towards noticing the ultimate same-ness (anicca, anatta, dukkha) of the particular experience rather than to get involved in being attracted or repelled by the content (specific taste, specific type of imagination) by investigating it and analyzing it.
Treat all experiences as ultimately the same and detach yourself from feeding them energy.
Here's the excerpt relevant to the fine, content-free nature of vipassana practice:
1 First, sit comfortably to relax your body and your breathing. We
call this first step of meditation the "preparatory practices", or
physiological adjustments, for tuning the physical nature. Basically,
you want to situate yourself so as to lessen any physical disturbances
or distractions. Then after your body is calmed, you start quietly
observing your inner thoughts and emotions. In other words, you simply
watch your internal psychological functions like a third person
observer. This third person doesn't interfere with what's going on, or
participate in the activities they're observing. He just stays there
watching, neither rejecting or clinging to anything; he simply sits
there silently observing.
[2] You continue watching your internal process of mentation until you
reach the point where you can clearly observe every thought and idea
which appears in the mind without any vagueness or ambiguity.
Naturally, you are not tightening your body nor mentally straining
during this practice. Rather, you always remain relaxed while clearly
observing your internal mental processes. After a while, you will
eventually be able to distinguish that the process of mentation has
three parts: a preceding thought which has gone, a thought which has
not yet arisen, and the immediate clear radiance, or mental state of
present mind. With continued watching, the separation of these three
states becomes quite clear.
[3] With continued observation, you progress a bit further and next
realize that the past, present and future thoughts never stay. Since
they don't stay they can never be grasped, hence we say that
"fundamentally, they have no base to rely upon". Observing the
appearance and disappearance of thoughts is called "observing birth
and death", for the coming and going of thoughts is a ceaseless,
never-ending process of arising and then disappearance, or decay. This
is the realm of birth and death. By observing this stream of birth and
death, you will gradually learn how to detach from the mental
processes, and you will become more familiar with the false mind of
consciousness. In other words, you will be able to drop the illusion
that our mental process is a fundamental reality. Rather, you will
gradually see that all mental states are ungraspable, transient
phenomena which come and go without end, and they're more like
insubstantial bubbles of foam or particles of dust which have no
fixity of nature. Because of their ceaseless birth and death and the
gap in-between, what we normally imagine as a continuous continuity of
thoughts is actually an illusion, like the unbroken wheel of light we
see when a stick of fire is spun in the air. Thus through this process
of inner watching, you will begin to realize that our mental state is
an ongoing process separate from our true self. The true self is
what's watching this play scene, so it's like an internal knower who
never moves. If you go from here to the North Pole and back, the
scenery always changes, but that inner knower never changes--it never
moves. In fact, it never leaves, and has never come either. It just
is. That's what we're seeking, though on a more profound level than we
can explain here. Now in watching thoughts without adding any energy
to the process, you'll begin to understand how dreamlike our
consciousness actually is because the reality it gives birth to seems
to be there and yet the concreteness of this reality is absent. It
isn't real. Phenomena are empty and yet they are conventionally real,
but this conventional reality is also empty. So eventually, through
observation with detachment, you'll reach the stage where you can
mentally relax while "giving birth to the mind without abiding
anywhere". Through continued observation you will notice that thoughts
or phenomena ("existence") are born from emptiness (mental silence),
and the existence of emptiness relies on phenomena. Existence and
emptiness are both manifestations of one nature--its single source,
our true self--so on the road of cultivation you don't cling to either
side. Both sides are phenomenal constructions, or false relativities,
so both sides are not real. Hence in shamathavipashyana practice, you
start to contemplate the mean between stillness and activity. In
practicing this inner watching, you'll get progressively better at
becoming mentally free because you'll stop clinging to or rejecting
your thoughts, emotions and sensations. Thus your mental awareness
will increasingly "open" and your ability to function in the world
will increase as well, so you'll actually be expanding your awareness
while saving a lot of energy that you'd normally waste in useless
clinging. Furthermore, your internal state of peace and calm will
progressively develop with every increase in clarity. Thus if you keep
observing the origin and destruction of thoughts while paying
particular attention to where they come from and go to, you'll
eventually obstruct the stream of consciousness.
[4] With the stream of consciousness disrupted, you will then notice a
momentary gap of stillness, or silence, between all your thoughts. In
other words, if you practice this method of inner observation for a
long time--by wordlessly watching thoughts without injecting energy
into the thought stream--the process of silent observation will itself
disrupt the stream of mentation. The state of mind in the immediate
present will gradually open up to reveal a tiny gap of mental quiet,
or emptiness; when a previous thought has disappeared and a subsequent
thought has not yet arisen, the mind will seem quiet. This mental
silence is not a gap of dullness nor stupor, nor should it be a forced
silence or blankness you create through suppressing thoughts. Rather,
it will be a lucid, clear and open awareness, and these
characteristics will gradually unfold as more time is spent in this
state. In other words, after quietly observing our mental processes
for quite some while, one will notice a tiny gap of silent pausation
between thoughts which we refer to as "cessation". If we continue
observing this state without effort and shine awareness on it, it will
gradually expand further and further. Looking into this gap of silence
is the process of "contemplation" or vipashyana. It's a quiet realm
similar to emptiness, but it still isn't the genuine emptiness of Tao.
Nevertheless, this is what we're initially after because we can use
this state to begin cultivating prajna wisdom.
[5] If you continue to carry over this state of watching the mind (the
process of silent detachment and immediate awareness) during all your
normal activities--whether walking, talking, sitting or sleeping--
you'll be able to reach the point where thoughts no longer bind you.
Gradually their volume will die down, your radiant awareness will
expand and you will be able to seamlessly enter into the real
emptiness of samadhi. In other words, if you keep observing the state
of cessation by shining awareness on this state, you will eventually
arrive at dhyana. Thus the practice of shining awareness on the
silence within is commonly referred to as "contemplating mind". If you
continue progressing in this manner by reaching further levels of
emptiness and shining wisdom awareness on any state of cessation you
reach, you will eventually acquire prajna wisdom, or transcendental
wisdom. Then you'll climb the various ranks of samadhi and enter into
the Tao. (Twenty-five Doors to Meditation: A Handbook for Entering
Samadhi, William Bodri and Lee Shu-Mei (Samuel Weiser, York Beach:
Maine, 1998), pp. 14-17)
Also, I would refer to the chapter on vipassana practice in Daniel Ingram's book. It says the same thing yuttadhammo and I said with some vivid analogies.
