These are some generally useful documents.

IMC.pdf
    An IMC training document by Mike Daas, with good review of many areas,
    and many practice problems. Copied from:
    https://pub.math.leidenuniv.nl/~daasma/IMC.pdf

polya.pdf
    A summary of Polya's problem solving techniques, from his book
    "How to Solve It". This is not specifically for math competitions.

strategies.pdf
topics-2001-2016.pdf
    These are two excerpts from this book: https://bookstore.ams.org/prb-37
    In particular the topics index could help us choose weekly review topics.

vtrmc-exams.pdf
vtrmc-solutions.pdf
    Exams and solutions from the VTRMC, a competition which ended
    after 2019. This competition used to be a "warmup" for the Putnam.