Lowes has a free kitchen planner that will save your plans for up to a year. It seems pretty similar to the one that the NKBA offers (National Kitchen and Bath.) Chief Architect offers some home planning software, but from what I understand, the learning curve is a bit steeper.

Sketchup is a really good introduction into 3D modeling, and you can download a free 30 day trial. For rendering purposes, you can download some plug-ins that are compatible with Sketchup, like Vray and Podium. It's been awhile since I have used them, but I believe it's possible to get free trials as well. There are plenty of tutorials available for these programs online. Good luck and have fun!

Tracing paper and Pentel with H lead.

Are you using it to create construction documents or simply to get your ideas down on paper? I use AutoCAD for all of my documentation, but there's a steep learning curve. Others use Chief Architect, but that also requires a lot of time to learn it. You could try SketchUp, which is actually for 3D modeling, but they have another add-on called Layout that converts your 3D models to 2D drawings. Most interior designers and architects don't use this for buildable plans--it's not quite as accurate. But, again, depends on what you need it for.