As a relative newcomer to Wikipedia I'm going through the evolutionary process that probably takes place with a lot of newbies. I started by correcting typos, and graduated to adding the occasional snippet of information to existing articles and contributing to some discussion pages. I've yet to create an article from scratch. I'm keen to upload some photographs but at the moment I'm intimidated by what seems like the complexity of the process. I'm sure it gets easier after the first time. Update: I've now begun to upload pictures and have so far only been threatened with one deletion by a bot. As yet I haven't added any images to Wikimedia Commons because it seems even more user hostile than Wikipedia. Having said that, I realise that a deliberate policy of deterring additions may be appropriate in order to stop the site being flooded with suboptimal images often featuring the same old views.
My 'specialist subject' is London but I like to get involved more broadly, wherever I can contribute something useful.
[some while later] Like a lot of contributors, I've found that the novelty has worn off after a while, and I'm not adding much nowadays, although I may return. My future contributions will probably be limited to text, though, because I'm fed up with my pictures being used on commercial sites without attribution.
I'm also increasingly being driven nuts by the number of pages that are topped by someone's addition of one or more boxes, criticising the article in question for allegedly failing to meet Wikipedia's standards for one reason or another. If and when the boxes go, or are at least relegated to the bottom of the pages, I promise to start contributing more to this site again.