Other than sourcing a instruction sheet online or through Tamiya USA in English the best approach would be:
Study the diagrams carefully, test fit the parts several times to be sure correct fit.
Build in sub-assemblies like motor, front forks ect.
If you have built another bike the assembly probably will be similar, use that as a guide.
Have pictures of the real 1/1 bike as a reference, or better yet a mechanical diagram break down like a service manual.
Good luck, if still intimidated shelve the kit and build a few other bikes before tackling this one. Ask to see the instructions to be sure they have a English version.