Forum Software
You have decided to run a forum and have some enthusiasm for it (and you will need it!) and you have a niche or subject area that you consider not to be too competitive. One of the first decisions that you need to make is what platform to run the forum on. This may depend on how much you can afford and how much flexibility or how much customisation that you want.
You could go for one of the free forum hosting options. The advantage is that the are free. The disadvantage is that you may be restricted in your bandwidth allowance. There will also be limitations on any customisation that you may want and the ability to make money from it may be very limited. If you later decide to move to a paid option with your own purchased software, then you will probably not have access to the database and have to start from scratch.
Of the paid versions of forum software, vBulletin is the market leader. The software for just a forum costs $195. vBulletin has extension customisation options and an active developer community which develops free and paid plugins. The easiest customisation is to find a good banner designer and insert a custom banner. There are no free versions of vBulletin and the version called nulled vBulletin is an illegal hacked version. It will not be supported by the company.
Other good paid options include Invision Power Board (IPB) and phpBB. Both are popular and have good support from the community with customisation and modifications.
