Spend some time searching out what others want and have done. Try to fit that into what you want to do. Larger tires are a common modification, but almost always require additional clearance. They also make the vehicle taller and more "tippy", a consideration for a daily driver. Lower gears are another common mod. When/if you change the ring & pinion ratio, you'll need to do both front & rear, and it will affect your speedometer. Only a few R&P ratios are available. If you change the R&P along with your larger tires, you can maintain some speedometer accuracy. Lower transfer case gears are probably the most common gearing change, and do NOT affect the speedometer, since the speedo drive is taken from the T-case output. If you plan your changes, you may avoid changing something twice.
If you live in a smog state, like I do (Calif), then consider the smog impact of any engine changes (Calif. requires a valid smog cert. when you sell the vehicle). Everything you might want to do has been considered and discussed before. Spend time researching what's been done and you might save yourself a lot time and effort. There are at least a half-dozen serious Suzuki aftermarket vendors. Most support several boards. Visit their websites; see what they offer, and what fits into your use of the Zuk.
These are getting to be old trucks. You might start by changing all the fluids and getting the rig running as best it can. You'll find the stock Samurai is a surprisingly capable vehicle. After you've lived with it a while, you'll have a much better idea what you want to do next.
