If you are new to the job market, have been out of it for a while, or just don't have that much experience, there are still several things you can add to your resume in order to make it a page long.
It's important to remember that lying or adding fluff is not the best method to create a fuller-looking resume. In order to find more content to use, sit down with a pen and paper and consider the following sections you can add:
Volunteer Experience: Think of any volunteer experience you've had, and how this experience may be useful in your job field. These may include designing flyers for the local animal shelter if you are looking for a marketing position, or managing a yearly food drive committee if you want a supervisory position. If you don't have any volunteer experience, then go get some. Volunteering a few hours a week in something you are interested in will not only help your resume, but will also help you make a contribution to the community.
Relevant Coursework: If you are recent college graduate, then this may be a great option. Make a list of classes you've taken during your college career that are most relevant to the position you are applying for. This shows perspective employers what you are knowledgeable about and may give you a head start compared to other graduates who simply list their part-time job experience. Listing 3-4 classes, along with 2 bullets of what you did and accomplished in the class is best.
Additional Education: If you attending any continuing education seminars, conferences, or retreats, it may be helpful to list them on your resume. This shows that you are invested in continuing your education and up-to-date in that field. Again, if you don't have any items to list here, attend a conference or take a night class at a local community college to boost your credibility.
Skills and Certifications: Listing computer programs you are proficient in (such as Adobe Photoshop), Fluent Languages, and any certifications you have will give employers a better look into what you can offer their company and how your background fits the description of the job you are applying for.
Unless you have been in the job field for 10-15 years, most resumes need to be 1 page long and easy to read. Most employers will only scan a resume and pick out the most pertinent information. Make you have a clear, concise writing style -- have a friend or relative proof-read your resume and check for any mistakes.