Why would you pay somebody to administrate your own money and give you random results while you can do it yourself?

Corporate bonds. I don't know the legislation in the US, but if there's any chance of you losing your money in case of default or anything. Don't do it. Don't look at how much things yield, but also evaluate how much risk there's behind those things. Nevertheless, if you think it's a good idea, as long as you diversify your portifolio and is investing at most 10% on it. The worst that can happen is that you lose 10% of your assets.

In my opinion, just invest with good diversification in businesses you think are good. Read a book or two in value investing and only invest initially in companies which have not too much debt and have had profits in the last 5 years, for instance. As you progress and get more comfortable, do more complex analysis and invest in companies with a more free criteria.

It might be boring at the first place, but that will prevent you from losing money. If you aren't working for a fund and isn't absolutely rich, just getting a paycheck at the end of the month, the yield doesn't matter too much. Just do the math for the case below and think for yourself:

You save 1k a month for 30 years. Every year you get a liquid 3% yield(I'm making it simple by excluding inflation). Compare this to with a 6% yield(DOUBLE!). Just check how the difference is small.

Now, compare that you saved instead 1.1k a month for 30 years. Only 100 more. There you go. Do the maths, all the yield doesn't matter. 100 dolars in that case is 10% of the total income your assets will have monthly, it's a lot.

The stock market won't make you rich, saving and having intentions of growing your assets will.