Don't forget to include a 'Power' skill in the framework for each allomantic ability. For example, a 'Steelpush' or 'Steel Allomancy' skill for steel, a 'Seeker' or 'Bronze Allomancy' skill for Bronze, etc.
It was discussed in the books that Mistings often had greater depth and nuance with their one ability than a Mistborn, who had eight abilities to learn to use. In other words, Mistings put more points into their one skill, while Mistborn have to spread their points across eight skills.
That, and when you come up with clever new ways to use the abilities, you will need a skill roll to make them work.