I have a form with several fields. I'm trying to auto populate the fields based on the users selection in the first field. So, kinda of like the cascading look up fields (country, state, city) but with more fields. Any advice on how to tackle this?
From the tags of your questions, I assume you're using an InfoPath form, and I assume for the selection that you mentioned you are using "select" control (dropdown), so the question is, are you using data source for the drop down or you are filling static data? In any case you can use the action rule on the dropdown list to fill other fields based on the selection you've made. It will be so easy if you connected the dropdown with a list in SharePoint, and based on the value that's changed it it's going to update other fields as well.
I usually end up doing things like this using a combination of JQuery and the Client Object Model. Depending on how complex it is you may just need JQuery.
What you need is $().SPServices.SPCascadeDropdowns method from SPServices jQuery plugin for SharePoint.
I've used this library a few times and it works pretty well for me: