Liquid investments are investments that could be turned into cash relatively easily and assume various forms, such as savings accounts, Certificates of Deposit, Money Market Accounts, and other interest-bearing accounts offered by banks. Normally, these types of investments are FDIC-insured and although they offer low rates of return, they are relatively less risky.
‡ Margin Rates: Effective since 12/21/2018, Fidelity 5.50% and Vanguard 5.75% for debit balances over $1,000,000. Effective since 9/28/2018, Schwab 7.825% for debit balances of $250,000 to $499,999.99. Call Schwab for rates on debit balances above $499,999.99, as its rates are not published for anything above this amount. Effective since 9/28/2018, TD Ameritrade 7.75% for debit balances over $1,000,000. Fidelity's current base margin rate is 8.575%.
Freelancing is the next best thing to being paid more for your full-time work, because professional work always pays more than unskilled. To find opportunities, let former colleagues or other personal connections that you’re available for freelance gigs. (Here are some ideas on how LinkedIn could be useful for that.) Or, post on marketplaces particular to your field. For instance, Mediabistro, a journalism site, allows freelancers to post profiles of their experience and services. Though these are more up to chance, designers can bid on jobs at 99Designs.com or submit a design at Threadless, to see if it will be crowdfunded. Elance-Odesk also lists many freelance opportunities, and you can also post your own services on Fiverr, although some freelancers say these services create a race to the bottom on fees and so are not very lucrative. If you're new to freelancing, here's how to set your rates, and here's how to negotiate raises with clients.
You could try advertising more, for example, by putting up signs around the neighborhood, posting about it on social media, or having people you know spread the word. You could also try doing it in a different neighborhood that might have friendlier people, or do it in a time and place where there's likely to be a lot of people walking around the area (e.g., near a church before the end of a mass). https://buzzingofferselfhelp.tumblr.com/