There is a huge amount of advice online about how to write a CV and personal statement and how to approach interviews.
The UCAS site has a video and lots of worksheets and advice on how to write a personal statement – at https://www.ucas.com/ucas/undergraduate/getting-started/when-apply/writing-personal-statement
TCD careers advisory has excellent resources on its site including interview advice, and CV and psychometric test resources which you can see at http://www.tcd.ie/Careers/students/jobsearch/apply/write_your_cv.php
You should also check out the University of Kent Careers Department which offers a wealth of excellent resources, many of them interactive. These include lots of sample CVs and cover letters, and advice on how to prepare for interviews including how best to talk about your competencies. Visit http://www.kent.ac.uk/careers/cv/cvexamples.htm