This is the question I asked two years back to many senior marketers when Google was changing its search engine algorithm very frequently. Well to answer your query, I must say since it is a new website, JUST DO NOT WORRY about PA/DA.
I hope you already know what PA and DA means. Work on your ON-Site SEO well, this is the best mantra for website ranking nowadays. Upload quality content on a regular basis. And if you are concerned about getting backlinks, then prefer authority sites. I believe one solid backlink is better than 100 poor quality backlinks. Create social media profiles for your website (Google Plus must along with Twitter, Facebook, LinkedIN, Pinterest etc) and maintain them properly and regularly. Start a blog section in your website. And yes, I have noticed some members commented above regarding "blog commenting" , I am not sure how much is it going to help nowadays. So, before you opt for that, read some articles on popular search engine blogs about how blog commenting effects website PA/DA.