Effective methods for managing work tasks? (documenting/remembering/prioritizing) [closed]

Question

I'm looking for suggestions on effective methods that I can use to document, remember and prioritize tasks at work. Many of the these tasks belong to a primary project, but they also exist for independent initiatives. The tasks themselves cover everything from development to documentation to discussions, with varying priorities, and deadlines ranging from right away to a few months from now.

Historically I have used a notepad to keep track of these tasks, with a star next to an item indicating it needs to be done and a check mark when it's completed. However, as I gain more responsibilities and more things to manage:

• it becomes harder to make sure I've done everything (because some things get lost 5 pages back)
• it becomes harder to remember what's most important to do next
• it becomes harder to keep track of dependencies between tasks

Has anyone found methods that have made their tasks easier to manage? I've considered adding some meta-data to keep track of what's most important and dependencies, or possibly switching to an app that could automate this (if such a thing exists). Something that's accessible anywhere would definitely be a plus.