For B2B marketing for enterprise level clients you want to use a combination of inbound and outbound marketing. You need to have good website, blog, and able to provide value to your prospect. You then can build up a list of list of potential connections using LinkedIn. Look in groups, job descriptions, etc to build your list. Get their Twitter profile and start following them. Favorite their tweets, retweet them for over a 2 week time. Outreach to them in LinkedIn or Twitter and mention how you have been enjoying their posts on Twitter. Direct them to a landing page on your website and try to set up a meeting with them. Have a CRM like Hubspot to track your leads.
Once you figure out an angle to get a opportunity to pitch your target - warm introduction, networking event, conference, cold email, cold call - this formula or a variation of it may be useful:
1) Provide Context (saw that write up about you in TechCrunch and...)
2) Show Gratefulness (best if you've received a benefit from them for example via a blog post they wrote that taught you something)
3) Recognize the value of their time
4) Have a specific ask!
5) Limit their time commitment
6) Make it convenient
7) Provide Value (example if they have active job postings indicate you have AND actually refer this posting to appropriate people in your network or look at their product/app, etc. and report bugs)
8) Indicate how you will provide additional value (for example our product has done X for Y and we think you will get the same benefit).
Keep it short... :-)