I don’t personally recommend rushing straight to blood pacts, take time to get to know the spirit before doing this.
Other people on here feel differently but blood is a very strong link and not one to give to a spirit you so far barely know.
It would be like marrying the first woman you see, with a pre-nup signed to give her everything, then just kind of hoping she’ll turn out to be a good wife!
At least give it a few days, I can understant the spirit wants a commitment as well before investing in you (humans are fickle) but rushing into this is not, in my personal opinion, a good idea. 
I recommend doing a serach on the forum for “blood” & “pacts” separately and together, using the search function. This is my general advice on pacts: Making Lasting Pacts That Work
If you do decide to go ahead, a lot of members use diabetic lancests (disposable and sterile, and probably authentic, people in the past would have used the best technology they had) to draw some blood. You won’t need much.