“Practical” and “practicable” overlap a bit in meaning; but by far the most common word, and the one you will have the most use for, is “practical.” The safest course is to save “practicable” for use only in describing something that it is possible to accomplish. If you’re not sure which to use, stick with “practical.”

Something impractical is not smart or efficient, but something impracticable is just plain impossible to do.