ANSWER - Animal communication can be a term to mean communicating with living creatures - like pets and wild animals or it can be used to mean communicating with creatures who have passed over- the deceased. We'll have a look at both.
Communicating with deceased pets in my experience is driven more by the pet than the witch. Many encounters of pets making contact with the living after their death are experienced by those not practising magic and would not consider themselves to follow a craft path. Those who speak of encounters with their pets who have crossed over occur usually say they occur randomly with no effort or deliberate intention to invoke on the part of the owner. However for somebody who intended to establish a connection simple techniques could be employed to make you more receptive to the pet. Putting yourself into a simple meditative calm frame of mind would give you the best chance of becoming aware of any attempt the pet is making to contact you. It is interesting to note that unlike contacting the spirits of the human departed there seems to be only a short window in which animals contact the living. Usually the connection is made within a matter of weeks and then disappears. We could speculate this is something pertaining to the nature of the soul of an animal - I'm not sure - but the pattern of contact very soon after death and then ceasing within a few weeks seems pretty established.
In terms of communicating with living pets - this article - sums up the basics on how to do it nicely. However it doesn't address the communication from a craft position so I would add a couple of points. I'd suggest it might be worth establishing a magical bond between you and the animal in question. This could be achieved with very simple spell work - perhaps plaiting your hairs together and sealing the ends with wax - the focus being that your essences are woven together. It is also worth trying to get into the headspace of what it is to be that animal. Silly as it may sound if I was going to try and build a spiritual connection between me and an animal I would also spend some time using mime, dance and visualisation to get an understanding in my head as to how that animal moves, thinks and behaves. Emulating the movement and behaviour of the animal will help you to start viewing the world from its perspective which will make it easier to tune into the animal's thoughts.
You ask about how to ensure you hear things that respond to you, I think the key to this is simply making the effort to being receptive. It is taking time on a regular basis to "tune out" of the mundane world and sitting quietly to reflect on whatever messages are coming your way. I always think a witch should also be alert to the signs that come her way. Sometimes an overheard phrase at the bus stop or a billboard you drive by can spark the thought that brings with it enlightenment. View the world in terms of looking for the lessons it has to teach.