Here is a giant list of great sites to practice some puzzles for fun! You can do them when you want or make a goal to do one or a few a day. My current plan is to do one reddit daily planner when I can (ideally once a day, but hard to do with work schedule.. and *cough* DOTA 2!).
I suggest making a solution for your work and organizing it by puzzle #. I put each puzzle # in a file labeled 0-50, 51-100, 101-50, etc.. then picked a naming convention and I make one class page for each problem then make an instance of it in the console app and pass in whatever variable (if there is one) from the main console program.cs. Pick one, two sites at the most and stick with it for awhile. It's harder to keep to a goal when it becomes too much so start small! Take a look at my setup!
My Reddit Github repository