Building a scale model from plans or offsets is a great way to start gathering confidence for a full-size boat building project. Even if only building in paper or cardboard, you get to practice the art of taking a plan and applying it to build materials. It's also a good way to experiment with design, yourself. You can check to see if you can produce a fair looking craft well before you commit the big money to messing up your garage or basement for half a year or more.
The only things you really need to get started are the plan set, some stiff paper, a scale ruler, mechanical pencil, scotch tape and maybe a thin dowel to help you trace a fair curve. Other options are some form of instant glue, balsa or bass wood sheets (1/16 or 1/32 thickness is what I usually use, I think), X-Acto knife, tiny clothes pins for clamps, masking tape and a surface you can cut and glue on without ruining your dining room table and risking the wrath of The Mrs.
A couple of years ago, I started out my boat building hobby as a complete woodworking novice. The eight foot plywood pram dinghy sitting in my garage was the first thing I ever set out to build, beyond some hastily slapped together skateboard ramps back in my high school days. Luckily, through lots of reading, online searches and cutting up bits of paper and modeling wood, I managed to muster up the faith in myself to pull off the first craft and move onto a second, with plans in a folder for a third this coming fall/winter. Also, the first paper model I built told me that I didn't want to build my first design pick, the D4/D5 dinghy and that I wanted to move on to something else.
From there I moved on to building models of a couple dory plans, the Gloucester Light Dory and the South Haven Dory.
Once I'd gained enough confidence with the paper models and had built a small plywood dinghy in the garage, I moved on to building in balsa and bass wood. I still don't bother to finish the models to a high degree, but what I do is a good enough representation that I can glean a lot of info about how the full-size version might go together.
The start of a Gary Dierking Wa'apa Outrigger, shunting proa version, seen completed above. I'm currently building the full-size tacking outrigger version in my garage.
An Ozarks Johnboat, built from a description, HERE.
P3 Proa, from these PLANS.
Roughly my own design, but heavily based off stretching the P3 by a couple feet and making it a tacking rig.
A sharpie that I cobbled together from sketches in Reuel Parker's "The Sharpie Book" and some plans on Duckworks Magazine's website for a sharpie by Howard Chapelle, HERE.
I also made a tiny free-sailing pond yacht and built a working half-scale model of a Marshallese toy outrigger called a RIWUIT. Made in a couple of hours from scraps laying around the garage and workshop.
In a nutshell, model making is fun in it's own right. It helps you learn the processes and build confidence that you might need for building large. It also helps you make better decisions about what you might want in a design, to begin with. Better to sort that out early, instead of getting halfway through a large build and figuring out it's not really what you're looking for in a water craft.