Learning martial arts alone involves a lot of re-discovering the wheel. You will be a hundred times better off finding anyone who has a solid grasp of the basics to show you and train with you - whether that's an official school or someone you meet online who is looking for a training partner. That's because not only is there the movement of the technique, there's the range, the timing, and more which you really only get when you're working with another live human being who is responding as well.
Also, seconding Dave's recommendation for general fitness, if there is a particular style you are looking into, you can see what kinds of conditioning they do in terms of exercises that might be feasible for you to train on your own (I'm thinking calisthenics, push up variants, squats, etc. not punching logs or anything.)