Choose a small starting point
Pick one maker, vehicle type, character, scale, or era. “Japanese diecast” is broad; “1990s Japanese sedans in 1/64 scale” gives you a useful filter.
A clear focus makes research easier and protects you from buying every attractive release you see. Your theme can always expand later.
Set the real budget
Count the item price, domestic Japanese shipping, international shipping, and possible import charges. A low listing price is not always a low delivered price.
Keep a simple wish list with a maximum price for each item. Waiting is part of collecting, and another copy often appears.
Record what you collect
Save the maker, product number, release date, scale, color, condition, and purchase source. Photograph packaging before storage.
These notes help you avoid duplicates and become more valuable as your collection grows.