I've been using Trello for years.
It's a cool product, and the reason I first came across it is because it comes originally from some cool people, Fog Creek Software (the same people responsible for Stack Overflow and the Joel On Software blog)
More than that, it's an easy and low-friction way to organise your life.
I run a whole bunch of Trello boards for different purposes, but there are some common themes and tips I can share with you.
Use attachments and rich content
If you use Trello as a flat set of lists, it really doesn't deliver. Much of the power comes from the ability to add links, documents, pictures and other rich content directly into cards.
Boring Trello usage
Fun Trello usage
Use the Power-Ups
There are many plug-ins available for Trello, and they're generally known as "Power-Ups".
One of my favourites is the Card Aging module, which visible changes the appearance of cards the longer they've been on the board.
You can enable Card Aging in ‘Show Menu’ and then ‘Power-Ups’ (that's where you'll find all the others too)
For me, the most important thing about Trello is that it adapts to the ways I work, which are constantly changing.
The fact that with a simple double-click I can create a new list and entitle it whatever I want is simple, but powerful; moving things between arbitrary columns is easy as pie.
So if I suddenly feel that I should organise my leads and opportunities differently, I just change some column titles, add a new list, and hey presto! new sales process.
Particularly when building a startup, where I'm doing All The Things (TM), having that ability to juggle things around is invaluable.
Get used to creating columns, dragging things around and letting the way you work dictate how you use Trello, not the other way round.
At some point you're going to have quite a lot of stuff in your Trello boards.
When that happens and you start having difficulty finding things in Trello (and your Slack, Google Drive, email...) have a look at CTX. Finding things in cloud tools is what it does.