I know there is advice (and very good advice at that) to generally not have startup/welcome screens in software.
I'm not sure I agree with that advice.
Your website, application or game's initial state is one of the most important things to get right. And by initial state I'm talking about the first launch, where there may be no user data yet, or subsequent launches for returning users.
…a lot of users will simply download it run it then be presented with a big grey empty screen which for our audience can be intimidating and overwhelming.
Some coaching is usually required to assist the user in getting over any initial barriers before they feel at home in your app.
By coaching, I'm talking about hints or tips to guide them in the right direction, not a 90s wizard (awful!) or a help overlay with a lot of text (also bad, in my opinion).
However, I don't think it's essential. Sometimes it's possible to create a first launch experience that so obvious you don't need any additional information.
Sorry, I couldn't find any blog posts with pretty screenshots of welcome screens (there's a potential opportunity for someone to create one).
I'd recommend keeping the info on the welcome screen to a minimum, and try your best to direct the user to whatever first actions they're likely to want to take.
Do you have some great looking artwork as part of the application? A welcome screen is an ideal opportunity to extend on the app's icon or other design elements.