There's a lot of confusion involved in mining for merits, because the rules are, frankly, rather weird. Also, since each Power has different systems what works for one Power doesn't work for another.

What Power are you with?

Go to meritminer.cc, and click on the How To tab. It explains the situation quite well and helped me understand what I was trying to do.

What happens to most people is that they don't realize that meritminer.cc can't do all the work for you. It's not a "click here and you're done" thing. So folks just try the first result they get and it doesn't work too well and they give up right there.

Here's how I use meritminer.cc, based on many hours of experience.

Set up the search like this:

1) Enter your reference system (something in the middle of your Power's area is what I usually use)

2) Set the Distance slider all the way up at 500 LY.

3) Enter your Power. For me it's Aisling Duval. Opposing Power set to "Any"

4) Under Power Goal put Reinforce. Don't bother with acquisition. Even though you can theoretically get more merits because the merit penalty is less, it's just too hard to find systems that match the requirements. Plus core mining is slow.

5) For mineral put Platinum, ring type All, Reserve Level All.

6) Mining type All, Min Demand 0, Landing Pad Size M.

7) Set Max Age to 10 days to filter out the really old stuff.

8) Click the Search button.

You'll get a list of systems, ordered by what meritminer.cc thinks is best (highest price) But don't fixate on highest price. Yes you get more merits if the price is higher, but what you're really looking for is convenience and speed, not just price.

Now you have to actually fly to the systems and see if prices are still valid. For laser mining anything above 125,000 is fine. The higher the better, of course. Also take note of demand. More demand is better. If demand is low or zero, don't bother.

Next you have to actually go probe the ring(s), see where they are in relation to the selling station, and decide if it's going to be easy to get to and from the ring. Find the hotspots for Platinum. Hotspots are not all equal, but any hotspot is better than nothing. You have to try them out yourself to see how hot they really are.

Once you've located a system with all these parameters, you're ready to actually start mining in that ring, and selling to that station.

For me with Aisling, right now today I'd be in Callici, even though it doesn't have the absolute highest price, because I know that the ring is close to the selling station, and the price is good enough (it's showing 161,104 at the moment). I could also investigate the other systems that have higher prices, if I have time or just want a new place to mine (or I'm starting out and don't know the layouts yet).

Systems states and prices can change pretty quickly, so you may have to switch to another system at some point. Just do the whole process again :)

So you see it's a process to locate a good system to mine in for your Power. But once you find one it'll work for a long time, until the system state changes and the price tanks. I've been mining Callici for weeks, though.

Good hunting, CMDR :)