I find it much easier today to rank junior miners and especially in gold..
Lots of places you can find their proven ore reserves and their financial status- at least being able to fund 2 or more years exploration and if sources of finance are available.
Then there are several resource conferences where it is easy to get free tickets so you can listen to their presentations and talk to their CEO, Chairman or geologist.
Not infallible but should get you a more than average chance of success.. Today my speculators portfolio has just exceeded my main portfolio. I initially allocated 10% of my capital there. Increase in Capital come with selling profitable trades. More recently more of my transfers to the SMSF CMT to fund pensions is coming from the speculators portfolio.
Great day today for resources. Most recent purchases are of ASX companies with projects in the USA, Canada or South America.