Orphaned pages gives you articles that do not have links pointing to them. Unless you do something about them, they are most likely to be forgotten about, because contributors will ordinarily never come across them or improve them.
Dead-end pages are those which do not link to any other. Sometimes this is okay, but often this indicates that the page has been created by a new user who is not yet familiar with inserting wikilinks.
Special:Randompage, as the name suggests, will throw up a random page. Usually, you can find something to improve in any page.
Proofread. This is one of the easiest ways to get started with helping with Wikitravel. While you're reading an article, watch for spelling mistakes, grammatical errors, or other writing gaffes. If you see one, edit the page and correct it. Wikitravel is now that much better -- thanks to you!
Reformat articles. Wikitravel has a manual of style for giving a consistent look-and-feel to our content and making it easier for travellers to find and use information. Just as with proofreading, you can do a lot of good just by reformatting or restructuring articles to match the Manual. Articles that need reformatting are typically stub articles, which usually lack standard headings and outlines. See also any articles in Category:Articles needing attention. The dead end pages, which list articles without any links on them, are also worth a look, as are the various Wikitravel:Syntax checks.
Organize the Geographical hierarchy. Work to help organise regions and to make make it easier to navigate the site.
Rate articles. Wikitravel has a system to indicate the maturity status of articles. This helps keep track of what stage an article is in and how many articles are at what level of maturity.
Expand listings. It can help a lot to take short restaurant listings, attraction listings, or other listings and fill them out. Contributors will often leave out crucial information about an attraction, such as its address, phone number, hours, or price. Often, this information can be found on the World Wide Web (see contributor research links for some starting points).
Check for articles for places you've visited. As with your home town, find articles for places you've visited. Check them for accuracy, add information, or start them new.
Don't limit yourself to things you already know. You don't have to have firsthand knowledge of a destination or topic to contribute to the article! Find articles that need work and do some research -- on Wikipedia, on the Web, or with other reference media -- to get started on working on that article.
Make outlines. Don't be daunted by the task of writing all of the article about Russia -- just get it started with an outline. People are much more likely to change or add to articles than to start them from scratch. We have a bunch of handy templates for destination guides, which you can use. If you only know a teensy bit about a subject, go ahead and add it in. We currently have a huge backlog of stub articles that shouldn't really be there. It is easy to create an outline for most articles and move them to the next level. You can help there.
Watch for wanted articles. The Special:Wantedpages feature of our software lets you see which articles have been linked to but not yet written. These are excellent places to get started -- you're filling in what is an obvious need for the travel guide.
Follow red links. While you're reading articles, if you see a link for an article that's Not There Yet, follow the link and add in some information. We're nowhere near close to covering all the info we need to have -- when you start a new page, we're that much closer.
Take Wikitravel with you. Before you go on a trip, try to find articles in Wikitravel about the destinations you're visiting. Print them out -- or download them to your PDA, or whatever -- and take them with you on your trip. Keep notes on what's right, what's wrong, and what's missing. If the destination you're going to isn't in Wikitravel yet, take notes for a new article to start when you get back.
Join an Expedition. There are several tasks for making a real travel guide that require special skills and talents. We've created special subprojects called Expeditions to organize the efforts of people who have these talents. Do you know a foreign (non-English) language? Help out with the Phrasebook Expedition. Can you draw? Try your hand at the Mapmaking Expedition.
Promote Wikitravel. The more people who read and contribute to Wikitravel, the better it becomes, and the closer we get to our goal of making a free, complete, up-to-date and reliable world-wide travel guide. There are a number of ways to promote Wikitravel; check to see if you can do one or more of them.
Help new contributors. New users contributing to Wikitravel can have a lot of questions and problems. Your experience with Wikitravel can make their learning curve a lot easier. Watch for questions in the travellers' pub or on talk pages and respond helpfully. If you see the same question over and over, add it to the FAQ. You can even add to the Help index for more complicated questions or issues. If there are help topics already in place that people seem not to see or understand, maybe you can help get that information out by reorganizing the help area.
Cheerlead. Nothing makes people feel better than knowing their work is appreciated. When you see a good piece of writing, or a great picture, or whatever, let the Wikitraveller who made it know that you liked it. Just a bit of encouragement on the article's talk page, or on the user's user talk page, can make a world of difference.
Shape the community. Our project is still young, and much of the way we've decided to work together is still untested. If you have ideas for how to work together better, please suggest them as new policies and guidelines. It doesn't matter how long you've been a Wikitraveller: you just might have an idea that will make things work smoother. At worst, you'll make explicit some policy that's currently implicit; that's a good thing. If there are policies already in place that people aren't following, maybe you can help get that information out by reorganizing the policies area.
Welcome new users. When new users come onto Wikitravel, it's nice to leave them a brief welcome message pointing them to important parts of the site. We normally wait until folks have created a user account and possibly set up their own user page. Welcome messages let new contributors know that they're part of a community, and also make sure they have pointers to important tools for contributing.
Clean up the travellers' pub. The travellers' pub, as the default place to put discussions about Wikitravel, tends to get a little crowded at times. For this reason people take turns moving discussions out of the pub and into the archives or to more specific talk pages. It only takes a few minutes, it helps make discussions more clear, and it's easy to do.
Make or edit policy and style guidelines. The policies and manual of style define how we work together to make a great travel guide. If you're working on Wikitravel and think there's ways we can make a better guide, or we can work together better to achieve our goals, by all means start a new policy or guideline page! We try to make decisions by consensus, so there's no guarantee that your idea will be accepted, but it definitely won't be if you don't suggest it in the first place!
Work on MediaWiki. The software we use for Wikitravel is called MediaWiki. If you know the PHP programming language, contributing to MediaWiki really helps Wikitravel. Fixing bugs or adding features makes it easier for other Wikitravellers to add great content.