First, you need to determine whether an opportunity seems like a good fit for what you're trying to accomplish. If you're an extreme introvert, it's probably not a good idea to spend money going to a convention to network, especially if you know that you're unlikely to feel comfortable approaching strangers and striking up a conversation. Similarly, if you're just starting out and publishing your first book, you probably don't need to spend a ton of money on fancy consultants that will develop a marketing strategy for you (if you have one book, your strategy should be to sell that one book and write another as soon as possible!

Second, you need to figure out whether you can actually afford it. While some financial risk is part of being a professional, there's a difference between taking a calculated risk and being irresponsible. Even if you're an extrovert and know you could make amazing connections at ThrillerFest, that's an expensive event to attend unless you already live in New York City. Between plane tickets and a hotel room in the city, you could easily spend several hundred, or even several thousand dollars on those four days in the Big Apple. If you have that kind of money to spend, great. But if that would be a financial hardship for your family, it's not worth going into sustained debt over (or struggling to pay your bills over), no matter how many great connections you make.

Third, make sure you're getting good value for your money. Look at what's really being offered and decide if the price is reasonable. This is particularly egregious in the entertainment industry, where "screenplay consultants" can charge thousands of dollars for notes on a writer's screenplay. They often justify this price by claiming to have been readers for reputable companies (like the movie studios), or claiming to have access to people at those companies who they'll pass your script along to if they really like it... but at the end of the day, we all know that writing is a subjective medium and, at the end of the day, no matter how much a script consultant, or developmental editor, or professional beta reader charges, they're still just one person with one opinion of how to improve your work. It's not a guarantee that addressing their concerns will automatically result in success. Don't buy into hype and baseless promises; make sure you're getting a clear sense of the service being provided (and preferably what kind of value other clients think it has)!

Fourth, look at your other options and decide whether this particular thing is the best way to spend your money. If you're a traditionally published author, there are a million demands on your time. Do you do a book tour? Speak on a panel at a conference? Teach a class? If you're a self-published author without the infrastructure of a publisher behind you, there are even more demands on your time and money. How much are you spending on an editor? How about a cover? And marketing? You need to be able to assess the various opportunities you have and decide which one will maximize your return on investment. Speaking on a panel might get your name out there to potential new audience members, but could that money be allocated to a better cover instead? Or another round of edits?