Much like people, business development hasn't changed much over the last 10 years. It's still all about relationships. However, it would be foolish to neglect the changes to our environment that can help you be more successful in supplementing your efforts.
A number of resources exist to help your in the research phase. For instance, reaching out to social networks is tops for our digital age. Things like Facebook and LinkedIn can provide some great insight and suggestions in the early stages of research on a particular Client or project.
Government business assistance agencies like https://www.fbo.gov/ (federal) and http://www.dba.virginia.gov/ (state of Virginia) offer free or discounted resources and events available for businesses.
When you've finally done your homework it's time to establish a plan and begin implementing it. It helps to do two things: focus and set your goals. Focus allows you to concentrate your efforts into the highest-payoff and the goals lets you take a step back at the end of the day and calculate ROI.
When you're actually developing those relationships understand that building trust and friendships takes time. Your internal goals as a business developer should be focused on 2 core elements: 1) knowing everything about what you're selling and 2) knowing every problem your Client is facing. This allows you to make an honest assessment and say "Yes we can help and here's how" or "No, but I can pass you along to someone who can help you."
If you think you've lost business by passing along a Client to another firm then think again. For one, if it works out that Client will thank you later when you continue to develop your relationship. Secondly, the firm that you passed them along to now owes you a favor.
BD is a lot like a garden in my opinion. You're planting seeds with the ultimate goal in mind, however all of the in between like preparing the soil, watering, pulling weeds and getting your hands dirty--the most important parts--are often times the time people either dread or neglect to spend their efforts.
But, much like a garden if you neglect all the work that goes into the development, your end result suffers. If you work with this in mind and focus on how you can REALLY help people throughout the tedious parts...not only in their lives but their own garden development...it makes harvesting your crop at the end of the season all the more fruitful.