With the arrival of the ego meter in Rising Star, skill is now a very important stat! Once you hit 1000 fans, if you have more fans than skill then your ego will increase, reducing the maximum number of starbits you can earn on a mission! There are three ways to increase your skill: Skill Boost cards, missions which award skill and other cards that also give skill.
Skill Boost cards can be bought in the marketplace or obtained in random card packs. They come in +1, +5, +10, +50 and +100 varieties.
You can also increase your skill by playing music lesson missions, missions specifically made to increase your skill. Below Battle of the Bands, there is a new Music Lessons tab.
Finally, there are other cards that raise your skill, like the Record Producer, as well as most of the rare cards that boost your skill along with other stats.
To succeed in Rising Star you will need to manage your ego by balancing your skill and fans, so don't neglect skill!