Finding the project is the hard part. Talk to Grad Students and Professors in areas you are interested in, ask them about a UROP. Grad students can help advocate with professors, and often end up doing a lot of the direct supervision of UROP projects. Professor Ballinger is the UROP coordinator, and from time to time you can find UROP projects from the department home page and UROP office page.
You need to discuss with your (potential) UROP supervisor what the project will be, how the results will be measured, whether its for credit or pay, and write up a project description you both agree on. Note that an undergraduate thesis is not a UROP project, but it can in part be the basis for one. you cannot be a UROP if registered for thesis. If funded, ask your UROP supervisor what the funding source is (you need the seven digit number).
NSE will ultimately fund all UROP projects for NSE undergraduates and Freshmen who are considering course 22, if other avenues of funding are not available. Initially (unless the deadline is passed) you should usually request direct UROP office funding first. If that is denied then your supervisor might have a sponsored project she or he can use. If your UROP supervisor is funding the project from a sponsored account or discretionary fund, they decide the rate of pay (usually between $9.75 and $13 per hour). UROP office funding and Department funding pays $9.75 per hour (as of AY12-13). For Department Funding, enter 3133900 in the "Account" field of the UROP application.
Peter Brenton, pbrenton@mit.edu, NSE Administrative Officer