> Should I get vBulletin license right away?
I started with a free phpBB forum, and eventually upgraded to vBulletin. However, especially if you use any customizations, it can be rather time consuming to upgrade. If you are willing to splurge on the $160 right away, vBulletin is a very wise investment. If you're not sure if you will make a return on your investment, or don't want to put anything up out of pocket initially, start with something free like phpBB and then upgrade.

> How can I grow my forum? How many friends?
If there was a big secret to this, everyone would be doing it. Do a search in this forum for advice I've given in the past. Post as often as you can, and recruit your friends to post. Each and everytime someone you don't know posts on the site, welcome them, answer all their questions, reply to all their posts, etc. Overwhelm them with attention. It will get them to keep coming back and they'll bring their friends. Even if the forum is empty, make sure everyone has someone to talk to, and that their posts are replied to very quickly, and they won't care that there are only 5 members.

> Yes, phpBB or SMF are good if you dont want to shell out for vBulletin straight away, but as dani said, migrating can be a pain.

> SEO is very important. So is advertising. If you cant afford any ads then post in google groups and usenet. It may be worthwhile to pay some friends to join up and use the community regularly, as people will be reluctant to join if they arent many other members.

> If you cant afford any ads then post in google groups and usenet.
Be careful - you don't want to be known as a spammer. Bad reputations within your industry can be hard to shake.

I do realize that migrating can be very painful, but should I take the risk of that investment with vbulletin?

Personally I think that $160 is well worth the time it would take to do a migration if you have plans of upgrading in the future.

You can always try some of the post exchange sites. ThePostSwap.com was pretty good, but it seems to be essentially dead now. PostSwappers.com is pretty new and might be useful. There are a few others, but I can't remember their names offhand.

First you can use a free script. I used it for 2 years almost and don't regret it. having to mod phpBB and create themes for it made me very relaxed with scripts. Now I can create a unique layout for any script possible since I have made my "schooling" with phpBB. The paid scripts have more features from the start, but don't expect them to make you a community. I see so many forums with default skin and features that won't make it. The script is not important: it's important to KNOW how to use it. I own 11 forums now. On VB, IPB, phpBB, SMF and MyBB. I think I kinda covered them all. And not one is best: I have things I like and dislike in all of them ...

So .. don't rush into spending money

You can ask for your friends help indeed, even if there are some topics they might not be able to support you. And the topic: anything you are passionate about and could talk for hours. Some topics are very "crowded", others are less (the niche ones). Chose carefully and prepare for a LOT of work