I just got burned chasing bond yield. I've yet to pick a good mutual fund. But over a long period of time I've seen my coins appreciate in value. Here are a couple thought:
Pick something you like and build on it as a specialty. 20 years ago cc coins were relatively cheap and I liked them. But somewhere along the line I lost my taste for the relatively common Morgans and started picking up cc
Seated coins whenever I saw them. Over 15 years the thrill of the hunt has been a lot of fun. These coins have appreciated enough, and are now mostly sold by specialists, so I can rarely afford to add to what I have. I've switched to foreign silver coins, which hold similar interest for me but are often way underpriced by dealers who can't sell them.
Remember that you have to beat retail. Some of the cc
Seated coins I have have tripled in price. However they sell wholesale, so I'd be very lucky to sell them for 2x, and more likely 1.5x what I paid.
Don't plan on flipping, unless it's in the very long term. There are millions of MS63 slabs of common date dollars. Adding a few more won't change the market. If you're interested in playing a market stick to bullion, which is what common MS63's are, plus the grading service fees. They move with bullion, but are much harder to liquidate.
If you want to slab something do it to a coin whose value makes the grading cost trivial. $1000 collectable coins, like 1795 cents in VF. I had a dealer advise slabbing only once, and ANACS identified pin scratch graffiti. I returned that VF 1795 cent to the original seller for a refund.