Write down specific goals (S). This is especially important with regard to the outcomes of the goals. If you set the goal "write more," this has no measurable outcome. How much more do you plan to write? How much are you writing right now? Come up with a specific number--maybe 500 words a day.
Make your goals measurable (M). This goes along with the idea of specificity. Set specific numbers that you hope to achieve. The measuring comes in when you keep track of your goal. Have you been writing 500 words a day, or for an hour a day? If not, increase efforts to set aside time to write.
Choose goals that are achievable (A). If you're in school or you have a full-time job, 500 words a day is a reasonable goal that most people could achieve with some effort. Writing 2,000 words a day is still attainable, but less so than 500 or even 1,000 words. Writing 5,000 words a day is impossible unless you have all day to spend writing. If you set unrealistic goals, you'll feel bad when you don't meet them.
Set goals that are relevant to you (R). Choose projects that you care about and the completion of which will make you happy. If you don't care about the goals you choose, it will be hard to achieve them.
Create time-bound goals (T). Set a specific schedule by which you agree to have completed your goals. This will help you distribute the work that needs to be done to accomplish it all by the agreed-upon date.