Tips:
Know your tools -- Be sure you are familiar with whatever tools you will be using, whether that is a pencil or typewriter for correspondence courses or an online courseware system. Do any tutorials that are available and run any setup programs. Read instructions for submitting assignments (etc.) and ask questions if you are not sure you understand.
Establish backups -- If you are taking an online course, do you have an secondary computer (work, public library, etc.)? An alternate email? Can you contact the instructor/students through some other means than the online courseware? Instructors: establish policies for alternate communications -- will you accept assignments by email if the courseware is down, or extend the due date?
Learn time management -- Especiallywith a new or unfamiliar tool, everything will take longer. Be sure you have enough time in your schedule. It is very common for online programs to state that students will spend 10-15 hours per week on their online courses (full time registration). For most programs, that would be the absolute minimum and, for most, too little to do a good job.
Brush up on your written communication skills -- for most distance programs, your primary method of communication will be written (written assignments, email, discussion boards, etc.) It's worth finding software with spell checkers. If you have a disability, temporary or permanent, that affects your written communication, take that into account when making your decisions about distance learning.
Start slow -- if at all possible, start with a single course when you start a new distance program. You are not only learning the course materials, but also the course delivery system.
Pay attention to requirements, technical and otherwise -- Should you have certain skills before starting the program? Do you need particular equipment, such as a computer with certain capabilities and software?
Get comfortable -- one of the biggest advantages of distance learning is being able to learn in your own space, so take advantage of that. Be sure that you have a good place to do your work, such as a computer setup adjusted ergonomically (online courses require a lot of typing), video displays that you don't have to squint at, and/or quiet space to read and write.