General liability is the most common and covers injury or property damage arising from your operations. It is inexpensive, and many landlords, venues, and larger clients require proof of it before they will contract with you. For anything involving physical premises or attending customer sites, this is close to mandatory in practice regardless of the law.
Professional liability, sometimes called errors and omissions, covers claims that your advice or work caused financial loss. It matters for anybody whose output is judgement rather than a physical product: consultants, designers, accountants, agencies. Contracts with larger organisations frequently require it at a specified level, which is a common reason first year businesses buy it.
If you hold customer data, cyber cover exists and becomes worth pricing once a breach would carry notification obligations or business interruption. Below that point, basic security practice reduces the risk considerably more than a policy reduces the cost.
Employees change the picture immediately. Workers compensation is generally required from the first employee rather than at some later size, and the requirement is set by state law rather than by preference. Establish this before hiring rather than afterward.
The useful question for any policy is what it excludes rather than what it covers, because the exclusions are where the surprises live. Read that section specifically, and check whether the cover applies to claims made during the policy period or to work performed during it, which is a distinction that matters if you ever stop trading.
Then check what your contracts already require. Many clients specify minimum cover levels, and buying below them means discovering during a contract review that you cannot sign. This is general information rather than advice on your situation, and a broker who works with small businesses will cost nothing to speak to and will know your industry's actual exposures.
Review the cover annually and whenever the business changes materially, since policies are written against what you described at the time. Adding a service, taking on employees, moving premises, or working with substantially larger clients can all put activity outside what was declared, and discovering that during a claim is the expensive version.