Risk tolerance? Time frame that you want to keep the money invested? Dividend a must?
My advice would be to find an investment manager you TRUST and shares your worldview as closely as possible.
Personally if I had a lot of cash I'd probably spread my precious metal investment 70% seniors and 30% juniors (I'm talking STRICTLY about the PM exposure of my overall portfolio). If I had less money to invest (think limited funds with a mortgage/family/responsibility etc etc) and losing some of the money wouldn't drown me, I'd be looking at more like 70% juniors and 30% seniors. A few big hits on juniors= small/modest investment turn into raining money (by the subjective standard of a smaller investor).
I'm hesitant to start listing off companies. Yes I know some good ones, but without more information I am not willing to do so. Even then, I'm hesistant.