My tips for job searching:
*Know what you want. It's important to be flexible, but desperate I-do-anything-you-ask-in-the-world-and-nothing-does-matter attitude isn't very positive. That makes whole the thing sound that you don't actually care the job they offer but you just want some
job. Don't still set your demands too high. About being flexible, show that you're ready to bend if they need it in some situations (overtime, shifts etc) but you still know your limits and aren't ready for everything. It makes you seem brisk.
*Know some of your good sides so you can bring up if they ask them. May them are charasteristics, may skills you have. It's good to highlight different sides depending on the job. Think what are your good sides for each job type. If you've education, job experience, hobbies etc that'd give you some extra points in job searching, it's good to consider them in that "good sides" list. Even small things counts, knowing how to use a cash register is merit for you if you try to have customer service type job in some shop type company.
*Know also some of your weaknesses if they ask them. Be honest but bring them up carefully. Saying "I'm freaking shy" isn't good for example in social field. Instead of it put it for example like "I'm pretty sedate (positive expression) person and it can lead to it that I'm a bit shy sometimes". Learn your good sides and weaknesses.
*Ask some questions about the job. It shows that you're interested just in that job. Tell that you're interested in new patterns etc that the employer can offer. If they ask what you'd gain from this job, answer also something else but money, for example experience or something.
*Be exact. If you get an job interview, be in time but don't hang out there hours before. Some minutes (5-10) beforehand is good. Be also clean and dapper. Put decent, clean clothes on, be sure your hair is well and carry yourself properly. Try to keep your shoulders back, don't lean forward because shoulders back seem you to look more open and receptive. Take an eye contact. If you for example feel that fiddling with something makes you feel a bit more calmer, put your hands in your lap if you sit and fiddle your fingers "under" your palms. Be polite.
And remember... try to be not too nervous, you're just an person, your resources are all humane just like any other applicant's too
Hope this helps even a bit.