Doing philosophy means more than just reading books, or listening to lectures. One thing it means, in addition to that, is that you have to live your life according to your insights, that you have to put them into practice. Your actions, views, and emotions must be formed so that they incorporate the insights you gain from philosophy; and that is decidedly something that must come on top of just taking in things. But it's not what I have in mind this time.
Articulating your own ideas, both in conversation and in writing, is just as important as learning about those you find already. There should be a balance between reading and writing, consuming and producing, taking in and bringing out.
If you're taking in only, it may keep you current on all sorts of things, but it will make you merely a dead mirror of the (more or less arbitrary) sequence of events that rolls out around you as you sail through your life. You can quote as many thoughts of others as you wish, if you haven't got something to add to them, don't connect them with each other, or build upon them so that you have to say something of your own, then it's not really producing, just parroting.
On the other hand, producing-only will have you spin frictionlessly in your own thought. Philosophy, as every other form of intellectual project, is based on a tradition and its records, an ongoing exchange with others, and a constant testing of your insights in your everyday views and actions. Your ideas must be informed by what others have achieved thus far, or you'll be damned to laborously re-invent the already known; you must also strive to incorporate what counts as state of the art, to renew and refresh, remember and reinforce, recognize and at the same time critically adapt that which has been achieved so far; and finally, your insights have to stand the trial of their worth in practice — the practice of living your life, which is, in the end, the only practice that really matters.
Moreover, philosophy must not be ignorant of intellectual achievement elsewhere, in any of the other disciplines that matter to us: the sciences and arts, all kinds of inquiry in social and political matters, local goings-on and global trends — in short, since we're interested in reflecting on what matters in our lives, we have to be aware of everything that can help to understand what is going on and find the best available attitude towards it. Traditionally, philosophers have thought about the concepts and ideas in all these intellectual trends, their methodologies and terminologies, about what's presupposed in them and what's implied. More recently, there's also been a movement towards focusing once more on the art of living well, which looks back to older traditions particularly in ancient Greece and Rome, where this has been the the undisputed primary goal of philosophy. And all of this is worth knowing.
But then, once more, to counterbalance the risk of becoming a mere sponge that just soaks up a lot of interesting information, you always need to try and make a contribution: come up with your own ideas, fresh views and interpretations, new concepts and visions; discover shortcut alternatives to well-trodden paths; produce new substance for discussion and debate by finding good arguments for and against commonly held attitudes; be not afraid of critically opposing what you find unconvincing, but remember to acknowledge and appreciate excellence wherever you find it (even if it is in a defender of a rival view); connect, organize, and systematize results from different fields of inquiry; reflect on their terms and methods; be a translator and interpreter when you find yourself in a dialogue between two parties talking past each other, especially if you are proficient in both their languages. Above all, be serious about learning the truth — and honor it by being truthful in everything you write and say, even if it means you have to retract a former opinion of yours. (Covering up the truth for fear of losing face is shameful.) Not only will you find a deep satisfaction in this: you will also note that your own insights grow more quickly and your intellectual reach will extend further than you'd ever thought possible. Take care.