What are some exercises I can do during the day to help me AP? Eg do you think concentration exercises would help you AP?
It depends on which way you want to achieve APs. Focus is a key to everyone, but there are various types of concentrations, and you must apply them to what you want to achieve.
If you want to have full willed conscious OBEs than you must learn how to fully concentrate on a thing to the exclusion of all else. An example of this can be concentrating on the breath. In this case you must concentrate on the breath and that alone. Every deviation on focus on breath is a break. Not only thoughts, but also feeling of the body, earing outside sounds, etc. In little words you must become the breath (this is called Dhyana). After, with more practice the same breath (and so "you") cease to exists (this is called Samadhi). This type of concentration requires much training, but with it you will be able to do many things more than just OBEs. However before having the first results it requires more time. Usually to be able to do OBEs you need at last to be able to hold concentration on a thing for 10 mins with maximum 2-3 breaks. This is the road called "Meditation" (also if that word has be used a lot meaning things completely different), or "Yoga". Usually the focus of this type of concentration is done with things that don't attract attention (as the breath, or a simple image), because you must train the mind with the most boring things.
If you instead want to achieve OBEs with the aid of sleep the concentration needed is a bit different. It is like a part of the mind is observing you going to sleep. In this case the type of concentration needed would be for example retaining a sort of conscious notice on what you do in the day, but without conscious interference with what you do. You must become like a "spy",so to speak, you will have to see but not be seen. Sleep is a good catapult for OBEs since it requires much less training. In sleep you are already in "yoga" unconsciously, so all you will have to do is to retain a thread of consciousness therein. Contrarily to before the methods used in this type of concentration usually have as a focus activities that can caught-up your attention, so that your focus doesn't wander in sleep.