I think that the simplest way to enter the Marketing project is to help on a LibreOffice booth. The only thing you have to know is how to use LibreOffice and what open source is about, not very difficult! You'll meet with other members of the community, you'll meet users from the very beginner to the most experimented one, you'll meet developers or people that have never heard about LibreOffice. I like it very much, it's always a friendly moment. On this booth, you'll see leaflets, stickers, sometimes tee-shirts, banners... all this has to be ready in time for the booth. Yes, you see where I am going: if you don't like to see people, you can still manage that the material is ready for the booth, that there is a timetable for the booth presence and the registration before the manifestation.
We (mostly Marc Pare, a big thanks to him :) maintain a calendar of all the events we are attending: http://www.libreoffice.org/about-us/libreoffice-international-events-calendar/

On this booth, we will need brochures and leaflets, something that we distribute to let people know about the product. But we can have brochure on how to become a developer, or a contributor too. So if you have some writing skills, this is something that can be worked on with the documentation and the design projects for example. You can also send your productions like calendars or bookmarks or ? you surely have more ideas than me ;) But we are greedy of all this, there is so much to do to advertise a product, you'll always be at your place if you come with real work.

There is a lot of conferences and manifestations going all over the world and we are trying to build a network of marketing contacts to represent the project as much as possible. Would you like to be one of this marketing contact? We will help you with the material, you can translate the official press release to inform the users and the journalists in your country, you could have a blog linked to the LibreOffice Planet to advertise the actions in your country, like events, hackfest or regional conferences. You'll never be alone, the group is here to help you achieve every thing with success.

Even if you don't want to have the responsibility of a marketing contact, you can still translate the press releases and the announcements in your language and send them to the discuss@ list of you language project. May be it's already done, but I'm sure that some help won't be refused.
If you want to invest yourself in the international marketing community, first you need to join the list where every thing is happening, to subscribe: marketing+subscribe <at> global.libreoffice.org. On the wiki, you'll find several information, see http://wiki.documentfoundation.org/Marketing. All is not up to date, so before working on an item, please inform the mailing list and discuss with others about what you want to do. You can work on press releases, usually Italo write them, but we always need proof reading, you can work on enhancing the website content (actually too verbose and not enough straight to find the right and useful information), you can work on the material I talked about for events. Another area is to try to get what's going on on the subprojects to reflect its activity in the press releases directed to market the community.
On a long run, you can help on the marketing strategic plan. This is a long and difficult task where your fingers will be highly appreciated. There has been some discussions about that strategy that you'll find in the archive of the list, but if you have a concrete proposal or experience on the topic, don't hesitate to discuss it. You see, also a lot to do on this project!

Oups, I was on my way to forget to talk about social media (you know twitter, facebook, G+ etc...). It's very important to relay all what is happening in our creative and enthousiastic community. Quick and fast messaging is a good media for that and a good place to express yourself.

So, you see, another good place to be! If I forgot anything, leave a comment, if you have questions, leave a comment, and even if you have nothing to complain to or ask about, you can even leave a comment ;-)