I do my best studying alone, because I've figured the subject out in my own way, which seldom translated to others who've reached the same level of understanding as me, so we'd waste time just figuring each other out. Also, I tend to not do a lot of studying when I can chat about something else, which I do.
Heh, also, if a friend isn't at the same point as the rest of us, I become the teacher. Though, teaching helps you learn a subject more thoroughly, and makes you be less Ni by having to actually think of the steps-in-between thoughts.
Strategies: How I write notes in the first place makes studying way easier. I divide a lined page into 2 columns, one 1/3 the page the other 2/3. In the left column is the main body of notes, separated into topics almost like encyclopedia entries, and in the right, beside each definition, is what I am defining. For example, if I was writing about what C is in physics (the speed of light), I put C in the right column, then the definition plus any needed references to other terms in the left. This way you can spot what you need to review really fast, and have all the info for it in one spot.
In school, my main motivation to study was fear of failure. Sad but true, not a whole lot of Higher motivation at work most of the time. While I do like the knowledge and learning, they main thing keeping my grades up was because I got them high and I didn't want them to go back down.
Consistency is mostly in habit. Make it easy to keep doing and I keep doing it. That notes thing is super easy, and with its obvious ease of re-reading I have no reason to want to write in another way.