Wikivoyage determines virtually everything by consensus. As a rule decisions are not made on this site by majority-rule voting. Please remember that the result of any Wikivoyage article will be the consensus view of contributors to that article.
Why consensus occurs 
When you edit an article you impose your view on it. But the person after you imposes theirs. Only that which all the contributors can accept ends up being left in the article. As a result most articles will end up being fair—that is a view that all contributors accept—in short—consensus.
Consensus is not just a policy; it is a fact of life on a Wiki. Because anyone can edit, anyone can change what is already there, or write something new or different. Then somebody else can come along and change it again, take things away, move things around or even change it all back to what it was to start with, perhaps even deleting the article entirely.
Wikivoyage does not use voting because, unlike consensus, it does not require that contributors present their arguments and carefully respond to each others arguments. In short, it depresses the kind of careful analysis and discussion that ensures that changes are made thoughtfully. Moreover, voting is complicated by the realities of the semi-anonymous online world; it is often not possible to ensure the one-person one-vote model of majoritarian democracy. There are a couple of pages specifically devoted to voting, most prominently Project:Votes for deletion, but even there, the voting model is not majoritarian and voters are required to justify their vote with a deletion rationale.
How to build consensus 
Consensus is most often built on the talk pages of the articles to which a significant change is being proposed. First scan the talk page (and its archives) to make sure that your issue has not already been discussed (if it has, make sure you understand the previous discussion, so you can respond to it). Then leave a message either at the bottom of the existing discussion or under a new section header, in which you explain your proposed change and your arguments for that change.
Consensus building can sometimes happen quickly, as a flood of Wikivoyagers pour in their support for your new proposal, exclaiming "Why didn't I think of that?!" More often, however, consensus building is hard work. Often more difficult than resolving disagreements is simply the matter of finding someone else who is interested in the issue at all.
If no one responds to your message, there are some options for soliciting comments. One avenue is to leave a request at Project:Requests for comment. If you are proposing a change where there is existing discussion, try leaving messages on the talk pages of the contributors to that discussion, asking them to comment on your proposal. Asking in the pub can also be effective, but it can get noisy in there—try the other avenues first.
Another way to solicit opinions is to simply plunge forward and, having left your arguments on the talk page, implement your proposal. If anyone cares enough to undo your change, they will need to at least explain why. Do not exercise this option, however, if your proposed change seeks to overturn an existing consensus—If the change is truly controversial, make sure you have some support before going forward with it.
Be prepared to wait. Add the discussion to your watchlist and be prepared for the fact that no one might be interested in this proposed change for a long time. While a wiki is constantly being edited and grown, individual articles may at times languish in obscurity before growing in leaps and bounds over the space of a few days. While no one may be interested in your proposal in the present, someone may come along later who agrees with you and is enthusiastic about working on your proposal with you.
Contributing to a consensus building discussion 
Address existing arguments. Having a strong opinion is fine, but simply voicing opinions is unhealthy for collaborating on a wiki. In objecting to a proposed change, it is necessary to address any specific arguments given in favor of the change, and to explain why you think they are not sufficient to sway your opinion. This process, of responding analytically to arguments you disagree with, will help you understand the other side of the issue (and help those who disagree with you understand your side), and therefore will help all parties involved to work together to come to a final resolution.
Keep an open mind as new arguments are introduced—there is no shame, only wisdom, in being convinced by other discussants and changing your opinion. As consensus does not require unanimity, it is considered classy to state that you will respect the consensus being built and stand aside if you find yourself alone in your position, even when you feel sure that your position is correct. This helps to build good will on the wiki (known to the wiki world as BarnRaising ) and to build respect for you and your account!
State a positive case. Say how you think things should be, not just how they shouldn't. Adding ideas, rather than just criticisms, leaves more room for compromise and can lead to an overall better solution. Who knows, maybe your idea will be the one that is ultimately accepted! If you can't think of a positive case, perhaps reconsider your arguments in that light. The current proposal may not be ideal, but may be the best solution available right now.
Avoid ad hominem. Focus on the arguments being raised and not the people raising them. Not only is it bad form, but it is an unlikely way to convince people of your point of view.
Status quo bias 
Overturning an existing consensus is very difficult to do. If hard work was put into establishing a consensus in the past, people will be reluctant to accommodate proposals that would undo that hard work. An established consensus will rarely be changed unless 1) new facts or compelling new arguments are introduced into the discussion and 2) there are compelling advantages to do so. If the benefit of your proposal is marginal, but would undo a consensus that took a lot of work to accomplish, it is unlikely that people will support your proposal.
In the case that a consensus becomes impossible—those involved have carefully responded to each others' arguments, but remain in disagreement—we stick with the status quo practice. (If there is no status quo practice, a compromise solution may be necessary.) This lends Wikivoyage a strong status quo bias. While sometimes frustrating when you want to make a change, this bias is deliberate because it encourages Wikivoyagers away from endlessly debating intractable issues and towards the purely productive work of adding new content, rather than sparring over existing content.
Slippery slopes 
As a project, we must be able to include X and explicitly exclude Z. A slippery slope argument—"'X' leads to 'Y' which leads to 'Z', therefore 'X' leads to 'Z'"—is usually a fallacy, and we do not want proposals to be vetoed because of unjustified fear of where it may lead us. Yes, we can discuss both X and Y and draw the line before Z. For example, we can discuss the best country music to come out of Tamworth, but a list of Golden Guitar winners would be out of scope. The irrational fear that we will become a discography should not stop a Wikivoyager from writing about a destination's musical importance. The reverse is true as well: the mere fact that we may include some musical information when relevant doesn't justify adding a list of your favourite mp3s for a bus trip.
Always remember that whatever you write will be changed by the next person to contribute. The more controversial or disagreeable your writing, the more likely it will be changed. You cannot stop this from happening. If the views of the various authors of an article disagree too much an edit war will ensue. Radical or controversial changes should always be discussed - first.
If you do plunge forward and make significant changes to an article, give a reason for it. Use the summary line on the edit form, and, if you feel you are making changes someone else might oppose, also put an explanation on the talk page.
Unless it is clearly vandalism or graffiti, simply reverting somebody else's changes will normally be unhelpful. If you disagree with the changes that have been made, try to find a mid point between your position and the other person's; something you can both agree on.