I'm not sure where he's jumping off from, but assuming it's ground zero with no fans at all, I'd first ensure that you have a Facebook/Twitter/YT/etc profiles for him, that are all connected together so that they're easily navigable from one to the other. Use some money on Facebook ads to get some initial fans so that your Facebook page isn't completely empty and people are at least discovering his/her music.
Having the music on Bandcamp as "pay what you want" or Soundcloud as the same is a good place to start in order to collect email addresses when people download the music freely. Use this small mailing list to notify about physical merchandise you have about a month after their initial download of the music.
I'd really advise against aiming to "get signed" as the goal of any promotional campaign you might do. Getting signed isn't all that it used to be, and for most indie artists, it isn't a good idea financially unless they've already established themselves with a fan base and are touring.
Labels look for artists who are already playing out regularly, have consistent crowd draw in a market (NYC is obviously damn difficult to prove yourself in), and who have been selling records without the help of a label. The biggest thing a label can do these days is help with promotion and distribution. If you haven't shown that you can sell to a "local" audience, it's not worth a label's time or money to promote nationwide.
Start small and email a few blogs every day. Over time, blog stories add up, a small fan base builds, and it gives your artists a platform to jump off of with their next mixtape/album.
If you have money to spend (read: About $10,000), hire a publicist to get solid blog coverage/traffic to your music video, and start a banner ad campaign on hip-hop tastemaking blogs 3-5 months before the album is due to drop. Any publicists worth their weight in salt in the music biz will charge about $2-$3,000 per month to promote your stuff full-time. The additional money will go to paying for advertising on the blogs you're getting coverage on.
Sorry I covered "a lot," it's just a vague question that you asked. Getting signed is kind of on the way out and growing slowly is the new way to gain momentum.
As far as "milestones" are concerned, I'd look at it like this.
Release the album/video day 1.
Next 3 months, email 400-500 blogs (that's about 5/day - should take you half an hour)
Setup Facebook ads on a $5/day budget for 2 months. Target people in the tri-state area.
Play at least bi-weekly after the album drops opening for bigger acts in the area and use the profit from these shows to fund the FB ad campaign.
Use Twitter (tweetadder or other automated software) to add/unfollow 100 people in your niche every day.
Send out an email once a month to your email list to tell them about shows in the area and about new merch you have available. Make sure you have CDs, shirts, and new stuff to offer, even if it's small.
Work on the SEO for your artist's sites. Make sure the tags are perfect for the Youtube videos he/she has uploaded. Make sure the FB page lists all of the other sites the artist is a part of. Really fine tune the social media stuff so his/her music is EASY to find and is accessible.
Run a contest for a free CD and continue to contact the local press and blogs about each of the bi-weekly shows you're having. Eventually one of them will bite. Get them on the guest list and buy them a beer. Good karma goes a long way.
