This. I can't count the number of "screenwriters" who have never sold a word because they either don't have the discipline to sit down and actually write something worth selling or they feel like someone owes them a break to get their foot in the door.
When people hear the job title "writer," they have this glamorous image of working for themselves and writing the next Lord of the Rings or the next Harry Potter or the next Da Vinci Code. Writing is a profession that is very difficult to break into because everyone thinks that they can do it... Consequently, the market is flooded with material that ranges from abysmal to mediocre. For every true gem out there, there are (at least) thirty mediocre products and a hundred horrible ones. The sorts of people who read potential products have to slog through a lot of bad material to get to the good stuff. The only way for you to sell anything is to put material on the market and keep putting material on the market until someone buys it.
If you're looking to break into writing, you need to be prepared for disappointment on one level or another. If it were easy, anyone could do it. Most professional writers aren't a Steven King or J.K. Rowlings. Many of them have to write in addition to some other job. My girlfriend and I are both published authors who have been paid and have books on shelves, and we both still have full-time jobs in other professions. I've only met a handful of people who get paid enough doing it to make ends meet.
For a little perspective... My first published RPG product paid $0.03 per word. At that rate, you'd have to sell a 100,000 word product every two months just to make as much as you could slinging burgers or pumping gas. That's not what a Monte Cook or a Chris Pramas or an Ari Marmell makes, but we also haven't been in the industry for decades and shaped the course of the entire industry either.
I'm not trying to make it sound like it's all about money. But if you write, you need to write because you have a need to write--not because you figure that you might as well get paid for it since you enjoy doing it on your own time anyway. There are thousands of "talented amateurs" out there (especially in our hobby, I'm frequently pleased by the quality of nonprofessional material). Don't try to write with any romantic illusions. If you make it in the business, it will be by writing lots of material and being around for a long time. Worry about writing and getting your material in front of eyeballs before anything else.
I don't think that writing adventures on spec is that great of an idea. If you write adventures for one person, only one person is going to read them or buy the product, right? So what you're doing is becoming a consultant for individual DMs, giving them help in their prep time. For screenplays, I charge $1.50-$2.00 per page for consultations. That's just for me to read it and write a short summary of recommended changes (the typical script being around 100 pages, the summary is usually 3-5 pages, so this takes me about half a day for $150-$200). My brain hurts thinking of getting an adventure outline from someone and then detailing around ten encounters (along with skill challenges, quest awards, et cetera) for around $2. You can't print the adventure you've just written at Kinko's for $2. You might as well write adventures for free.
I don't know how true this is. I know a lot of people who got their start in the movie business at film festivals and working pro bono and then taking percentage points from sales or just getting a break from someone who loved their project. I'm just breaking into the RPG business myself so I'm not sure how much this applies here. However, my gut feeling is that getting your material in front of eyeballs is always a good thing, whether you're getting paid for it or not. If it's good, the right people will eventually notice.
