This section is dedicated to take away all your "I wish someone had told me that before I went!" experiences. This way, you can spend less time settling in, and more time making new friends in your chosen hostel.
Beijing is a massive city with a lot to do for the traveler. You obviously have to visit all the traditional tourist attractions (the Great Wall, Forbidden City, Summer Palace, Tiananmen Square, etc.), but there are thousands more things to do based on your interests. You can immerse yourself in the Chinese life by walking around different areas, you can stop and eat at small cheap restaurants, go to parks... the subway system is very good, cheap, clean and safe. So pick Beijing hostel close to a station, you will have to walk quite a bit anyway... but at least if you're close to the stations that'll help.
Beijing hostel staff are also usually very friendly and eager to help, so they will be your best resource to find ways to enjoy Beijing. They can write a few Chinese characters for you, tell you where to taste the best tea, help you fix a bike if you use one, make copies of your passport for your next visa, and they can tell you where you can eat dog (!) or the more traditional Peking duck for cheap, and how to go clubbing safely. All Beijing hostels will also have organized tours to book (try to chose the ones which don't include shopping, even if they cost a bit more because being forced to stay in jade or silk stores for hours instead of enjoying the Great Wall like you expected is not the greatest way to spend a day in Beijing).
Beijing hostels in particular and hostels in China in general usually don't have a shared kitchen for their guests to use. However, they generally do provide fast-food sorts of meals (which are usually much more expensive than food you can get from a nearby restaurant). Instead of eating the pizzas and BLTs at your Beijing hostel, be adventurous and try out the local specialties. We recommend that you plan to stay at least a week if you want to truly enjoy seeing Beijing.
