I would suggest the 6 following rules for judging the wisdom of investments
1) Do not use any Bank Financial Advisor. They only offer you that Bank's products even when there are products more suitable for you provided by other suppliers. Ask yourself why most mis-selling claims involve banks
2) I would also pass on a rule that my daughter drew up
"Do not invest in any financial product that you do not understand"
In other words if you do not completely understand what exactly every penny of your money is going into dont put your money into it. Almost all of the mis-selling scandals have arisen because people have brought complicated investment products which, usually their bank, advisor has promised have all sorts of benefits but which the investor hasnt fully understood. Read all the small print and if you do not understand it dont invest in it. it.
3) Do not be greedy. If your building society is only paying 3% anything offering 7.5% is risky,no matter what the person trying to sell it to you says.
4) Beware property investment, particularly overseas property, unless you know the country, and understand the property market there and have actually seen the property you are investing in and have had all the details independently checked out by a British lawyer with experience in that country. Never, in any country including the UK accept a sellers estimate of rental value and the availability of tenants without checking it out yourself with several local estate agencies. Make sure any mortgage is sterling based. Never take out a mortgage based on an overseas currency.
5) You would not put all your money on a horse you had only heard of from someone who cold called you to give you a sure tip for the 3.30 at a race course you have also never heard of so do not buy shares or other investments from a cold caller who rings up offering you shares in a company you have never heard of but whose shares you are told will rocket in value in the next year. They wont.
6) Never throw good money after bad. A bad investment doesnt come good because you invest more.