With the fierce competition for attention getting more ardent every day, it never hurts to do research before starting a forum. Any forum. There was a time when, if your site was more commercial, or you intended to approach alternative revenue sources (financial backers, which could be anyone from a bank, to the local cafés, to your parents), then a more business-y plan was indispensible. Now, it really depends more on what kind of research you're planning to do, and what purpose it's going to serve in giving you a strong[er] start.
Technical Research - Not all boardware was created equal. Likewise, your learning curve, sharp though it may be, was not designed to learn MySQL, PHP, HTML, and CSS coding in the space of two weeks. Either you come to foruming with little bits of each, a lot of one, maybe two, or absolutely zippo. No matter what, there's a lot of forgiving software out there that can make you look like a megastar with very little effort. Still, you should make it part of your Five-Year Plan to learn something of what makes your board work, so as not to be left high, dry, and sending support tickets all over creation when trouble comes. And it will come. If you are the kind of person who thinks cellphones, ATMs, PDAs, and even word processing applications have too many bells and whistles these days, then you're in for a shock if you get the latest versions of IPB or vBulletin. These are deceptively powerful programs, and you want to make sure that the things you choose to build them with are things you can maintain and understand.
Marketing & Money - You are going to have to consider how your forum is going to appeal to others. A thought soon to follow is going to be "How am I going to pay for all this?" While actual start-up costs remain within reach of even the minimum wage-earner and allowance recipient, getting reliable hosting and paying for a software license are big commitments for anyone. Not because the physical price is so high, but because you're making a product that hundreds, maybe even thousands of complete strangers are going to make part of their daily routines. You must research reliable sources of revenue, consider advertising and affiliate programs, and decide if you're in this to get rich or die trying. Unfortunately, the odds are high on the latter. Most forums fold or get completely revamped within six months of their launch dates. No backer or advertising partner is going to want to lash themselves to the mast of a sinking ship. You have to prove your staying power, in most cases, or present a solid case for growth to any potential investors. This means numbers, facts, and projections based on reality, not just "I think it's a good idea."
Designing & Image Resources - Perhaps, you've heard the phrases "Not everyone's an artist," but "Everyone's a critic." Taken together, we understand that we all know what we like to look at, and some of us are even competent enough to make those visualizations real, but by and large, you're probably going to have to farm this skill out to your betters. There's no shame in asking for help, certainly not when you're calling the shots. Any competent graphic artist is going to treat you like a client, discuss your options thoroughly, and provide a clear set of alternatives within the limits of their talents. Like the boardware, not all artists are created equally, either. Some are more proficient at logos and banners; others, skins and buttons; another subset may be better at 'storyboarding' a site, planning out each screen your guests encounter. Bear in mind, however, you often get what you pay for. The skills of an apprentice may come cheaply, and look it. You should also be clear on whether such a service is permanent position at your site, or just contracted for a single job.
Demographic/Sociological Research - What is a niche? What is a theme? What makes target audience? Although these and many other topics are addresses across The Admin Zone, you will probably find their counterparts in real-world literature, and in related fields of industry and behavioral study. Certainly, your selection of categories and topics is going to be of interest to YOU, but what about people who are NOT you? (the other six billion of them) You might want to ask yourself, in the first place, "Why am I making a general discussion forum when there are hundreds of thousands of them already out there, and even most specialty boards have one among the rest?" You want first to figure out why your board needs to exist, and that will lead to a better understanding of who is to populate it. This cannot be "just anybody." Depending on how deeply you wish to delve into this sort of thing, you can be as simple in your response as "other teenagers" or "other people in my profession," or as complicated as "middle-income homeowners with dogs, a Volvo, and a bizarre fondness for vacuuming." The more acurately you can envision this Ideal Member, the better suited your board will be to their company and those of people like them.
Personnel & Organizational Psychology - Congratulations, you're somebody's boss. Strangely enough--and just like being an artist--this is not a job description that suits everybody. Managing the talents of others is skill that cannot be replaced by charisma, alone. You have to enforce guidelines, settle disputes, make important decisions, and maybe even fire and upset people. It is really how and why you do the latter that gives insight into your character and your facility in this role. Should you hire friends as moderators? How much access do you want each staffmember to have? Where are you going to do your hiring from, if not your own board, and why? Again, there are many answers to these across TAZ, but it is ultimately a matter of how well suited you are to saying, "I cannot be all things to all people, but barring that, let me find a few who do X, Y, and Z really well, and I'll trust them to do some of it."
The one thing that seems to be a common denominator here is that you can't be master of them all. That's when it becomes important to RESEARCH YOURSELF. What are your own strengths and inadequacies? Can you own them and move on, or do you not trust others enough to delegate authority, responsibility, and accountability? Making your board dreams come to life is not unlike getting married or starting another serious relationship. There's money involved, people's feelings are at stake, and you're probably going to be concerned about what everybody's perception of you will be like. If you are not committed, honest with yourself, and capable of finding help when you need it, then no amount of research is going to replace that.