A licence is your permission for others to use the work within the specific terms of the licence. You never license yourself, you license someone else or someone else license you.
If you are the sole right holder of a work and you do not assign or transfer your copyright interests to others, you retain all rights regarding the work.
Licensing your work under a CC licence does not make it impossible for yourself to use it commercially in the past, present or future.
Of course, permissive licences like CC-BY might decrease the commercial value of your work since anyone else could reuse your work freely with minimum restrictions. But that does not prevent you legally from use your own work for commercial purposes.
The exact choice depends on your wish on other aspects of using your work. For example, CC-BY-NC would require the licensee (essentially, anyone else not having another overriding agreement with you) to attribute/give you credits in order to use it non-commercially only, but they may remix and adapt your work as they wish as long as they credit you and the purpose is non commericial.
You may also add an ShareAlike (SA) requirement where if the licensee creates an derivative work based on your work, they must license their derivative work using CC-BY-NC-SA as well.
The last kind, CC-BY-NC-ND (NoDerivatives), would not only require credit when the licensee uses your work, but also prevent them from creating derivative works from your work.
