First, when it comes to a budget you have to have an idea of what amount of money you are going to make each year, month, week, and even day in some cases. You also have to know how to properly use extra money that was not figured into your budget. It is always better to figure on making less and spending more than making more and spending less. Second, if you struggle with budgeting, then using budgeting worksheets might help you. These can be printed out or just kept on your computer if you prefer. Most of the budgeting worksheets that are out there will break everything down into the categories for the bills that you need to pay. This is very helpful and will allow you to stick to the budget you set up for yourself.
I'm a fan of MS Excel _ my apologies for those who have issues with Microsoft _ because I find its powerful calculations are easy to manipulate to help me better understand my finances. It doesn't really matter though which spreadsheeting package you use so long as you are able to calculate your amounts effectively. There are commercial budgeting worksheets available but if you want to create your own its a simple process.