Software Engineering and Project Management are the two things that you are asking about. Software Engineering is the steps of gathering requirements, design, implementation, deployment, and maintanence. The Project Management is the how's of executing the Software Engineering.
There are alot of factors that will affect how you organize and plan a project. But the basics of really understanding what your client needs not what he thinks he wants is a key problem. Basic methods of obtaining the goal of understanding a clients needs is to describe the project in different ways. This is where UML and modeling comes in. From descriptions of the project in english paragraphs, business models, workflow charts, prototypes, to complex state models, the purpose of them all is to better understand the project (both you and the client to understand better).
I would pick the parts of the project that have the most risk, risk can in terms of time, complexity, orgainzation you are working with, business, about anything. Whats the first problem that comes to your mind, and it doesn't have to be about coding at all, tackle that first. Then work on the next one and so forth, where these risks can change over time and come back up to the top as the project progresses.
Ok, thats my two cents on structured Software Engineering and Project Managment, but what about real life. Well, in simple terms remember client feedback is important (prototypes help with this, you don't want to making something they didn't want), define phase of the project and have milestones so you and the client feel that something is getting accomplished. And always remember to make good backups and failure recovery measures (Test your software before you give it to the client).
