You're getting very close!! The next thing I would work on is the aesthetics of the joint. IMO, you should be using less tails that are wider and slightly narrower pins. Take a look around at some of the more well known woodworkers and look at their proportions. I would highly recommend looking around Derek Cohen's website and check out some of his dovetail articles and furniture builds. Another great resource for laying out the dovetails is Christopher Schwarz's method. This works great if you're looking for a symmetric tail layout and you can fine tune the size of the pins by whatever is left over after dividing across the width of the board. This will make more sense after you watch the method. On wider case work I prefer a layout that has a wide tail in the center of the board with smaller tails on the outside but this is completely personal preference. Either way I think your tails should be much wider than what you have there especially in thicker stock you're using. Keep on cutting and don't be afraid to just make a box out of your practice pieces. I think it's a waste of material if you don't complete the process. You also learn other aspects of the craft such as grooves, fitting a bottom, making a lid, installing hinges, etc.