An introduction category
These are brilliant. There's nothing harder than trying to make first post as a new visitor. With so many conversations going on between other members, it's hard to automatically fit in and join the natural flow.
Adding an introductions section to forum allows visitors to make an extremely easy first post. This also allows others to boost their post count by responding and welcoming them to the forum.
The benefits of this are members feel more welcome, get an increase in user posts, and it makes it easier for new members to jump aboard and get to know everyone.
Competitions can create a real buzz for forum. There is one thing that is very improtant though which can either make this a great idea, or a very bad idea.
If you are going to have a great prize, you really need to have a great way to promote your competition. If people dont know about your forum and competition, then hardly anyone will participate. Put all you can into word of mouth, links etc. you can even try contacting other webmasters to see if they will help advertise the competition on thier sites!
One great competition I have found is to do it based on referrals. The member who gets the most of his friends to join up and get posting will win a prize. PayPal, eBay items, or coupons all work great. Be creative and see what can come up with!
Create a unique look
This is extremely important. With literally millions of forums out there, what competitive edge do you think will separate you from another of the same topic? That's right, a great looking forum.
When starting a new forum, many people tend to stick with the default template. I cannot stress enough how bad this is. Whilst the default theme does look nice, it is far too common. Visitors to forum will know this and think you either don't know what you are doing with a forum, or you are not willing to put in enough effort to make it look different. This will make them think it is not worth their time and effort posting on forum.
You do not have to be a programming genius in order to do this. I found that simply changing the colour scheme and a couple of graphics really works wonders. Spending just a couple of hours on your CSS and images can be the difference between visitors signing up or going to another website.
Make alternate profiles
One technique used when starting a forum brand new is to make about 10 profiles and get posting. Whilst this can seem like a good boost it can look pretty bad. Each time you post, your personality leaks into it. People can quite easily tell if its the same person or not. It also requires a great amount of effort to have 20 or so conversations with, trying to present different views and make it look good.
Instead, contact your friends. Ask them politely to sign up and help by making a few posts. Offer to get them a beer or something if they do, or just reward them with your kindness. Get them to tell their friends about site too. Word of mouth is great for getting people to join forum.
Also, if are lucky enough. Get friends to put a link to forum on their websites. Can also link back to them.
Paying for Posts
There are quite a few services out there that will offer to do posts for $. Whilst this may look like a good post-boost to forum, it can really harm it.
People aren't dumb. When start seeing about 20 people only making 10 posts then never returning they will notice somethings up. When feel that members are bots or paid people they will most likely leave. Who the hell wants to get into discussions with "fakes"? Members want to have REAL discussions and get to know each other.
In my experience that this can really hurt a forums reputation.