As a reminder, the formula for nectar is 1:4 sugar to water. Only use regular sugar--no organic brown
sugar, raw sugar, or powdered sugar. Some raw and brown sugars have honey or other additives that can be harmful to the birds. Do NOT add coloring or buy the premixed nectar that is red. It is not necessary and may be harmful. Also unless your water is especially hard you don't need to boil the water. Just ensure that the sugar has mixed in well. Be sure the feeders are clean. That black stuff is mold that can cause the nectar to spoil quickly. What feeders you use isn't as important as being able to clean thoroughly (and types of feeders is a subject for another post). Hummers are territorial so if you are attracting more than a couple of birds you need multiple feeders. Just don't fill each feeder all the way as you need to change the nectar every couple of days in the summer heat.
If you aren't getting birds at your feeders, you'll really enjoy watching the hummer cams. A Rockport group, WWN, puts out a camera that streams live. Check it out at http://wwnrockportcam.com/live/.
For a real immersion into hummingbirds, plan to attend the 2014 Rockport HummerBird Festival, September 18-21. Hundreds of hummers can be seen at homes that open their gardens to festival-goers. People often comment about the number of hummers that swarm around (I suggested it was like swarming flies one year there were so many circling me.) and how close you get to them. It's free to tour the hummer homes and maps can be picked up at the local Chamber of Commerce office.
Oh, but I can't forget...the festival also features a shopping mall with everything birds and birding. I'm planning to find a bird bath! In the meantime, I need to put out fresh nectar. The birds are getting impatient.