The question was pretty much a simple one. "How To Get Otaku Friends?", and though the question was simple, the answer like most things is not.
Friendship like anything always starts from one of the most important and grounded rules; to have a friend, you must first be friendly. Not really an easy thing to do these days since so many people are either not really who they seem to be, or are merely posing as a friendly person on the world wide web.
One of the biggest setbacks to most otaku in general is going to be their attitude. You will either be presented with a fan of anime and manga that has an overwhelming sense of superiority, or is still firmly wedged in their "closet otaku" phase of fandom. Either way the path of meeting other like-minded friends of the fan-base will be a difficult task.
When dealing with other otaku on the internet it is easy to find debaters and flamers, and this makes fans more out of arm's reach than merely meeting them in the public, but again finding an otaku friend in public, in real life is pretty rare.
For one; most of the people that I see, that are fans of anime and manga are pretty self-withdrawn when they are in the public; browsing through the DVDs and manga volumes, and don't openly engage in conversation, even though I myself are right there with them shoulder to shoulder browsing with them. The second thing is that even if you were by some miracle to get a fellow of the fan-base to acknowledge your presence and say something, there is a good chance that you will encounter the odd-ducks the same as me.
Those few seldom seen nerds that are so buried in the medium that they are practically non-functioning in any normal outside real world setting, and have only sneaked out into the light of day to buy anime and manga, and thus are incapable of speaking about anything except anime and manga.
Now, I like a good conversation about anime the same as anyone else; but at some point, I will eventually grow sick of hearing about the legendary super Saiyan Broly, and how his sheer existence is the stuff of supreme nerdish wet-dreams. Or how the characters in Ouran High School Host Club are so dang relatable to you.
Really? The characters in Ouran, are relatable? What a load of crap. But still, you are going to encounter that sort of thing in your travels looking for otaku friendship, and if you let minor things like that get under your skin, then chances are, you are not ready to be a friend.
Many so-called-otaku are probably going to be under the age of 18; so unless you yourself are around that age, you will most likely have little worldly commonalities between you and them. Chances are if you are a younger person, then and you want to be friends with an older otaku, then you will find little patience in them for your ignorance and over-the-top fan-gushing over every perceivable new hot anime or manga that gets released.
I'll admit, that in all honesty it is sometimes better not to have otaku friends. They seldom let you have your opinion, they chide you for your tastes in entertainment, and they get really pissy when you like something other than what they like, or worse, dislike something that they feel that you should like.
I do not believe it is possible for two people to remain friends based on their fandom. It is best to throw that out the window, and just be their friend based on themselves. The worst thing that has ever happened to the American Anime Fandom is the advent of proclaimed opinion.
I normally don't have anything against people's opinion, except for when they imagine that their opinions are paramount to mine and everyone else's, and then it just turns into a nasty grudge match of words; them trying to convince me something is good, when I clearly don't like it, and or me trying to convince them to abandon their evil ways, and walk the straight and narrow of anime and manga.
It's possible to be friendly, it's possible to be associative, but it just is not possible to be friends with other otaku, at least not based on the otaku aspect alone. To be a friend of an otaku means you are going to get crapped on, pissed on, balled out, griped to, shoveled, and shoved. You are going to have to overlook all that to be their friend, or else not at all.
Abandon your opinions, and take them, and the fandom in stride, or you will be like the thousands of other otaku in the world. Alone and lonely looking for companionship, or at least one other fan that wants to watch Bobobo Bo Bobobo.