The answers given so far illustrate your most fundamental goal – deciding what it is you actually want to do with Blender. The field of CGI production has so many aspects that it can be confusing and even a bit overwhelming trying to sort it all out at first, and Blender has capabilities in nearly every aspect of that field.
Setting out to “do it all” can scatter your learning time & energy, so your initial goals should probably be tightly focused on what appeals to you most. Maintaining interest is a very important part of starting out because some parts of the work can end up feeling like pointless drudgery.
If you like creating characters, then definitely focus on learning the modeling tools, and how to create and manipulate armatures (rigging). Start simple with the latter part, though, because more advanced rigging techniques can be very complicated. Learn the basics first & build on that foundation of experience. In this area of focus I’d say that a minimum 1-year goal is to have a fully modeled & rigged character (even if a relatively simple one) ready for animation. Along the way you’ll probably want to head down some side-trails into materials and texturing, and the basics of animation (posing & setting keyframes). Advanced topics for this focus would be learning the Sculpting tools and how to incorporate high-resolution sculpts into easily-animated character models, more sophisticated rigging techniques, and going beyond the animation basics.
If you like settings & environments, modeling is the base skill set, but you also want to get familiar with various kinds of lighting and rendering techniques, as these play a big role in determining how well your work is perceived as “realistic” (if “realism” is your goal). This is also a good path for “object” work – cars, spaceships, cooking utensils, weapons, tools, containers of endless variety, all the bits & pieces that fill up our world. A goal here might be to create a fully-detailed room, then light it and render it so that the viewer feels he or she has just walked in through the door. This is regardless of whether your room is mundane or fanciful.
If like Atom you enjoy animation the most, then take advantage of the many sites that offer free models and start practicing the fundamental of designing on-screen motion. Start with objects and work your way slowly up to rigged models, because you’ll need a foundation of simple methods to really do your best with the more complicated subjects. You’ll want to learn about how to render to some form of animated sequence, and how to convert that to a playable format – the options here are not only broad but also often confusing, so it takes some study. Atom’s suggestion of a 10-second short is a good start but for a 1-year goal I’d say try telling a complete story in 30 seconds. It need not be a complicated story, in fact simpler is often better. But it should be a complete story, not just a demonstration of certain techniques or methods. Along the way you’ll most certainly have to do some study on the art of filmmaking and story-telling in film, which is fundamental knowledge for even very short movie-makers – uh, I mean, makers of very short movies
If “special effects” – aka SFX, VFX and just plain ol’ FX – floats your boat, then target learning how to use the Compositor and the Video Editor (VSE) to combine simple model work with live video footage. This includes learning about motion- and camera-tracking, match-lighting and perspective matching, matte options, using Blender’s Render Layers, and again, the various output options leading up to a final deliverable movie product. You’ll want to learn a about all the physics sims as well, as they are often instrumental in the creation of various effects sequences. Here a 30-second short as a goal is also feasible, but need not be as tied to a story (although it’s probably a good idea). With FX, sometimes just showing all the cool stuff you can do in Blender is enough. Innovation is also very desirable in this field.
This is just a basic primer of the many paths through Blender you can take. The best advice is to plot your path carefully and try to not get sidetracked, at least no farther than necessary to learn subjects associated with your main goal. Even when keeping to a well-planned learning track I’m sure you’ll find yourself picking up good info and skills in other areas, that’s almost inevitable. Also do regular spot-checks on your progress, assess how far you’ve come, maybe even consider changing paths if some related subject has really sparked your interest along the way. No sin in that.