Wagn is about organizing information, so it can be helpful to do some thinking about how you want it organized -- programmers call this Database design, and it's usually done by specialists who use arcane incantations to talk to the computer. With Wagn, anyone can do database design, and the good news is, it's really not that hard! Here's how it goes:
First, pick two or three things that are the big important things you want to keep track of. Say you want to track your record collection on Wagn. So you decide Records and Artists are the two main things you want to keep track of. Once you've picked them out, create a cardtype for each one. This is just like creating a normal card, except you select "Cardtype" in the Cardtype dropdown menu (when you're on the New Card page).
Now pick out some things you want to track about each Cardtype. Say you want to track the date and producer for each Record. Create a form for Record and include date and producer. You'll probably also want a section where you can enter whatever you want about the record so you could include note as well. Now when anyone creates a new Record card, they'll be prompted to add a date, producer and notes. You can do the same thing for each cardtype that you create. Or, if you don't know what kind of information you'll want for a cardtype, just see what people use it for over time and add a form later.
The nice thing about Wagn is you don't have to get this process just right the first time. You can add and change forms, and create and rename cardtypes at any time — so your structure can grow to accommodate things as you bring in more and different kinds of information.