Product

1. Product worked well - I can't emphasize this enough. I know it seems obvious but we all can list examples of the opposite. Be very careful putting software out to the world to try if it doesn't work. You have one or two chances to impress someone, so you better nail it. Very rarely will the trial customer stick through a bad experience unless you happen to be in the enviable position of offering software someone has to buy and has no other options.
2. Ease of use - the product is very easy to use. It is simple and straightforward. Plus, they provide lots of videos to teach users how to use the product. I find this particularly helpful. It is great to have user manuals if you want to go deep, but a handful of simple, short videos is an awesome way to train new users with minimal effort.

Process

1. Rules of the game - they did a very good job designing what the pilot includes and what I would be able to do. In their case, I received 500 emails to try the product (I signed up through SalesForce AppExchange). There were no limitations on features or number of campaigns.
2. Provided true product experience - the trial provided functionality for the whole product suite and all features. I was able to fully understand what I would be purchasing and what I could do with it. I think other companies that provide trials, but only expose a percentage of the product features, are making a big mistake. In the case of Vertical Response, they make their money based on volume so it fits nicely in their model.
3. Sales person was awesome - I received a very polite phone call and email asking if I needed any help. When I talked to him, he invited me to a weekly webinar to learn about the product. (Small aside - this is a great strategy and one I plan to start with our company). He did a great job on the webinar and really helped me get the most of out of the product.
4. Make it easy to sign-up - Once I decided I wanted to use the service, it was very easy to enter my credit card and get started. It isn't always so easy with business software, but it should be to take as much friction out of the process as possible.

Marketing

1. Word of mouth - I had heard of this company from some of our customers, so I was already inclined to give them a fair shot. I can tell from my trial experience that they take care of their customers based on their responsiveness. Granted I was in their sales process at the time but I'm assuming the same responsiveness will apply as a customer. Bottom line - you HAVE to take care of your customers and delight them. If you pull this off, your customers start selling for you.
2. AppExchange - they have done a nice job of promoting themselves on AppExchange. It is very noisy in there, and tough to figure out which solutions to use. I thought they were able to rise above the noise effectively through their write-ups and obvious success.

Have you trialed any software lately? Any lessons learned you would like to share?