Lime is generally considered one of the easier woods to get an ember with. The lime should be almost yellow in colour to achieve the best results. Post a picture of your set and the dust your producing.
Other woods commonly used are Western Red Cedar, Hazel, Sallow, White Willow, Elder not an exhaustive list by any means. Remember to start slow maximise the friction at the hearth end of the spindle and minimise the friction with the bearing block. Long slow strokes with the bow applying firm downward pressure should achieve lots of thick smoke and black dust forming around the edge of your spindle. Once you have a good thick dark smoke slowly build up your speed and increase the down force until you have a nice big self sustaining ember. Fire by friction is more about good technique and choosing a piece of wood with fire in it. make sure you can mark the spindle and hearth with your thumb nail. it should leave a mark with light pressure. Too soft and your spindle with collapse and wear too quickly. Too hard and the base of the spindle will polish and become a frictionless surface.