First of all, make sure you have a Skills section within your resume. In this section, you should list all languages, platforms, products and tools you have had experience with. For each item, mention a degree of knowledge or the context in which you learned/used it.

For example, say:

• Proficiency with C++, Lisp, and Corba.
• Some experience using PHP for the development of secure web-applications.
• Advanced Perl and Regex knowledge.

Be sure to include all buzzwords and variants of such words within your Skills section. This is important because many placement firms use automated software that scans your resume for particular skills or keywords that their clients specify. 

For example, a company looking to hire a web developer may search a database of 5,000 resumes for the keyword HTML. It is to your advantage, therefore, to include as many such keywords as relevant. 

For example, instead of saying:
Experience in web-development and the use of Structure Query Language with Databases.

Say something like:
Web-Development experience with HTML, ASP, and JSP. Proficiency with SQL, MySQL, Oracle, and SQLAnywhere.

PROFESSIONAL EXPERIENCE SECTION
This is the section in which you list your previous work experience. Label this section "Professional Experience" -- not "Jobs", "Job Experience", "Work Experience", or anything else.

List your jobs in reverse chronological order -- starting with your current or latest position.

Through the positions you list in this section, you should try to display a gradual progression in your career -- for example try to illustrate how, as your career has progressed, you have shifted into positions with more responsibility and more impact. Mention any promotions. 

If possible, include specific numbers or figures that quantify the impact of your jobs.
For example:

• Managed accounts that generated over $25M annually.
• Decreased site load-time by 30%.

Omit Professional Experience that is irrelevant to the position you are applying for. In particular, there is no need to mention projects or jobs that you held over 10 years ago unless the item significantly adds to your resume. Elaborate on the jobs and projects that are most relevant to the position you are currently seeking. 

Note: if you are a recent college graduate or have little Professional Experience, you may wish to list your Education/Degrees first. Be sure to focus on listing all relevant course work, projects, and technologies that you have worked with.