There are no right and wrong resistance training routines. Each individual has to determine what best suits her needs and goals. Here are several sample splits I've compiled for you to try if you're looking to break a plateau or your workout's gone stale.
Day 1: Chest, Shoulders, Triceps
Day 2: Rest
Day 3: Legs, Calves
Day 4: Rest
Day 5: Back, Biceps, Abs
Day 6: Rest
Day 7: Rest
A pic of an athlete who obviously followed a carefully strategized training split.
Day 1: Chest, Biceps
Day 2: Legs, Calves
Day 3: Rest
Day 4: Shoulders, Triceps
Day 5: Back, Abs
Day 6: Rest
Day 7: Rest
Don't forget to add at least 3 cardio sessions per week, ranging from 20-60 minutes each. For maximum results, vary the duration/intensity of each session, as well as type of equipment used.
Prioritizing a Body Part
If you want to prioritize a particular body part, train that muscle on your first training day of the week. Follow a 3-day split, rest one day, and train the weak body part one more day that week lightly. Here is an example for someone prioritizing their back:
Day 1: Back (heavy)
Day 2: Legs, Calves
Day 3: Chest, Shoulders, Triceps
Day 4: Rest
Day 5: Back (light), Biceps
Day 6: Rest
Day 7: Rest
An example of what YOU might look like if you prioritize back training!
Day 1: Back (heavy)
Day 2: Legs, Calves
Day 3: Chest, Biceps
Day 4: Rest
Day 5: Shoulders, Triceps
Day 6: Back (light)
Day 7: Rest