1) VUL
If you want to insure and invest, the right way is to buy term life and invest the rest. By buying a VUL you’re actually doing the same thing, only at a much, much higher cost.
2) Annuity
Especially those variable annuities (another “V”). Be informed that your sales agent/broker can get upfront commissions as much as 6% of whatever you put in. Ask yourself where that money comes from.
3) All kind of guarantees
The very nature of investing is to take risk to get (expected) return, and guarantee comes at a price no lower than the value of the guarantee itself. Everything else is too good to be true.
4) Mutual Fund
Mutual funds, including index funds, are high on costs, low on efficiency, and very low on tax efficiency. Unless your accounts only allow for mutual funds, notably 401(k), 403 (b) and 529, try Exchange Traded Funds, or ETFs. If you can’t construct a sensible portfolio with the over 170 ETFs available, you’re either too smart, or too dumb.