Question

how can liquidity be improved

Answer 1

It depends upon whether you are talking about the government's role in stimulating commerce or a company's effort to reduce the buy-sell "spread" in its stock price.

Central banks increase liquidity by making credit more widely available, at lower interest rates.

Corporations sometimes try to improve liquidity with stock splits. Making the public more aware of your company's products and "mission statement" by advertising also helps.

Answer 2

If you are talking about selling products that have few potential buyers aware of them, use something like EBay. If it is real properety, use a realtor or online advertising.