You can set muscle memory and get familiar with the dynamics of cross-stepping whilst moving and/or turning; here's a quick instruct for a longboard. This length is great for land paddling AND cross-stepping!
Step 1: Materials!
2) Old hardware, Trucks, and Wheels from your old skateboard/cruiser/longboard.
3) Grip-tape is optional.
Step 2: Template
2) Once you're happy with your outline, use a jigsaw to carefully cut out your board.
Note: I used my Sector 9 Luke Nosewalker 55" longboard as a template.
Step 3: Flex and Rigidity...
Step 4: Mock Fitting!
Then, fit your trucks and wheels and make sure everything is set and straight!
Step 5: Refinements...
Start by getting some rough sandpaper (of your choice and going to town on all the splintery, crude edges, then go to a finer grit and smoothen out your work even more.
I like shaving/sanding off a few layers of the ply to make the tail mimic a tail-block:)
Step 6: Finishing Touches...
Find a picture of your favorite longboard and copy the paint job, or do something original with stains and waxes or oils --you can never go wrong when it comes to art!
Apply your grip-tape directly on top of the board, and feel free to make designs with the shape of your cuts.
Step 7: Gift It!
To break from the norm, try land paddling once in a while and really get those core muscles into your surf training!
You can see that this board is about 62" in length...
Step 8: Safety, and Details...
My girlfriend and I absolutely love surfing. When we are short on time, landlocked or within 3 days post rain and drainage, we maintain by skateboarding (long-boarding) and land paddling. Here are a few shots of my beautiful and talented GF (cross-stepping) on her S9LNW longboard.
Don't forget to consider wheel size, durometer, truck height and width, and all the minutiae of technical information once you get better and want to dial-in your skateboard:) Google is your friend! (May I suggest: Silverfishlongboarding.com, for all your skateboarding needs).