Someone said I should only focus on one agency. Is this good advice?

Sadly it's insane and a few out of touch tutors still say this (this advice comes from someone who actually works in the industry). It's a bit like an actor leaving drama college and hoping to get the lead part in a major movie. Sure you should have something to aim for (but do your homework first, don't just choose one because your ego is so big you think you are only fit for the top).

It's important to have goals. But to ignore all others...madness! Remember, many great creatives had humble beginnings - two highly acclaimed above-the-line Creative Directors started out in the in-house direct mail department! If you have the talent (and the right attitude - no one hires arrogant students anymore) you'll probably make it there some day.

Although you may be advised to avoid somewhere that does 100% rubbish, many less sexy agencies will teach you valuable skills and give you the experience you'll never get in college. While you are there you'll be earning and it won't stop you targeting those agencies you really want to work at. Do be realistic though, every student wants to work at Mother, HHCL, AMV, Saatchi or BBH. Alas, dedication is no substitute if you have the wrong book or the wrong attitude. Sorry, but that's life.

The chances of getting a job, even with a great book, are slim (most of us creative directors may only hire one student team a year). Don't let this put you off. But a warning- if you haven't worked in 2 years because you've been too proud to take anything else the chances are you'll be even less likely to be hired because the team that did take a job now has a portfolio of real work, real experience and an award for something. Also you'll probably have a chip on your shoulder that'll make you arrogant and bitter. The DHSS is the least attractive agency of them all.