There's no one solution that fits everyone, because there are different styles of organizing and planning. The DayTimer/DayRunner approach works for many. Simple lists or scraps of paper work for others. There are fans of Getting Things Done (GTD), which is based on the premise that if one gets the tasks & things of one's life into a "trusted system" and reviews that system regularly, all will be well. Some systems are top down, and focus on goals; some are bottom up (like GTD) and focus on low-level tasks.

D*I*Y Planner 3.0 is a free planning system based on GTD. Since it's free you could try it out at no cost to you. There's a free application called ThinkingRock that runs on Windows or Mac OS that implements GTD that you could try out.

There's a free DayTimer-like software planner called EasyNoter available for Windows that you might try out.

MindTools has a number of articles & tips you might find useful - also free.