Drop the distractions. Another way to be friendlier is to notice everything that's going on around you instead of trying to beat the new level of Candy Crush on your iPhone. If you're tapping away at your phone, burying your nose in a book, staring at your computer, or even just picking at the paint on your fingernails, then people will think you have better things to do than to talk to them. Instead, look ahead, smile, and be ready for what the world has to offer you. You'll be surprised by how many more people think you're friendly and how quickly they come your way.
Tapping away at your cell phone is rude especially when you're actively engaging in conversation with people.