Don't avoid working with legacy code.

Embrace
Like many developers who have only entered the developing world in the past 5 years, I have been spoilt by languages such as C#, tools like Visual Studio and good in browser debugging tools. It isn't until you deal with technologies like Visual Basic 6, xslt and VBScript that you realise how much today's tools and languages do for you to shield you from some of the older practices. I'm all for this and hope that languages continue to evolve to be easier to use, but I also think that any developer who hasn't tried working with legacy code should jump at the chance to do so.

Evolve
Since day 1 as a professional developer I've been asked to work with legacy code as well as modern code, and what I've found is that legacy code really makes you work and think about what you are doing. It encourages you to get creative with both debugging when the debugging tools are not up to par and writing code for basic tasks that you would normally expect to be handled by whatever modern framework it is that you normally use. It basically forces you to write real code rather than just follow the best practice of the time (something you should always do when possible, but in the real world, sometimes you have to code dirty to get the job done) a skill which you can then use when dealing with modern languages.