Advancing Your Relationship
You might have a crush on an Otaku friend and not know how to progress to Otaku boyfriend or girlfriend status. Although it depends entirely on the other person being interested back, there are many ways to let them know that you like them, some subtle, and some not so much.
First, though, is that you have to realize not all of your opposite-sex friends are going to like you back. Some of them may be interested in other people, or you might not fit their type. Realize this, and be able to move on if you are quickly rejected.
The best advice is to see if that person wants to spend more time with you. Invite them to do things like see a movie, go to a park, or play videogames together. If they say yes to doing these activities with you, then they might enjoy spending time with you and you can get closer to them. If they say no, perhaps they are not interested in you and you should move on.