Greenlaw, S. A. (2006) Doing Economics: A guide to carrying out economic research. Boston: Houghton Miffin. ISBN 9780618379835

Neugeboren, R. (2005) The Student’s Guide to Writing Economics. London: Routledge. ISBN 9780415701235

"Doing a dissertation" in the 'Studying economics' section of the Economics Network website.
If you Google 'dissertations in economics' you will find many websites that claim to provide help and guidance. Some of these will be helpful to students e.g. the guide by Paul Dudenhefer; other links take you to guides provided by various Universities for their students. However, care is needed here, as students may also find offers from tutors prepared to write their dissertations at a price...

Other chapters in the Handbook for Economics Lecturers augment this guide. In particular:

KimMarie McGoldrick, Undergraduate Research in Economics

Jeremy B. Williams, Plagiarism: Deterrence, Detection and Prevention