Ask HN: What'd you do to get your first 100 users?

In my opinion reddit is very underrated in terms of customer acquisition. It's a target community of early adopters who are willing to start a conversation with you. For my start-up, 900dpi, I got our first 400 users from reddit after failing miserably through other channels. We found our best success in /r/web_design but have also looked at /r/frontend and /r/webdev. Sometimes your best traffic comes from comments in other peoples posts (where redditors are asking for a product like yours or discussing a problem that you solve). Our product has been picked up on a couple blogs too after being discovered by the bloggers via a reddit post.

I've also had luck with some other niche community sites such as Designer News. The important piece here is to try and integrate yourself into the community instead of just spamming them with links to your website. Get involved in conversations about things other than your start-up (people notice this and appreciate it). Make friends with the moderators. When Designer News was still private with no search capabilities I wrote a quick search engine built on sphinx to index all of the posts and make them searchable. Not only did this get me an invite to the community but also sent some nice traffic to my start-ups site via a small link on the search page.

I've had little to no success with twitter and facebook, although I might be doing it wrong. Some of the targeted communities that you can find through google plus look somewhat promising, but I've yet to fully explore these.

Our most vocal power users are people we know personally, or met at local events (our local co-working space).

If you have a product that may generate profit, e.g. a SaaS application targeting businesses, not a money burning consumer-app train (see: twitter or another photo album app) one of the strategies that work is cold emailing:

0. Identify and name your target group, e.g. commercial real estate agents in CA.

1. Find these people on Linkedin using advanced search option and invite them to connect.

2. Once connected you have their e-mail address, so send them a short e-mail (better response rate than InMails) describing the business problem and your solution. Short means 3-5 sentences, no attachments, just try to attract their attention.

3. Don't forget about follow-ups.

4. They will reply if interested and bam, you have a lead! Now it's time to set up a call and go into details.

5. Rinse and repeat. Stay persistent, you should send at least 20+ every day. Track response rates and adjust, you should achieve at least 5-10% easily.

Not post on HN or Reddit, that's for sure.

Some of those suggestions (eg. comments) may represent a risk to search ranking. From what I understand, Google considers comments a negative signal. Perhaps it's only duplicate comments, though. Can someone more experienced than I am please provide their perspective here?

you might try your local chamber of commerce. I believe one the mail apps tried that. probably need a general business app.