Bigger tip is great, and also try adding some flux all around the joint, and that will help transfer the heat better. Just make sure it is flux for electronics.
Just as an FYI, you should have a collection of tips for your iron. I have tips from 1.2 mm chisel style up to 3.2 mm, with 4 sizes inbetween, and having some super fine tips for soldering surface mount components and even things like the pins on a Grayhill switch like on the MP573s.