While many people see purchasing a single-family as a steppingstone into multi-family, that is not necessarily the case. If you want to focus on multi-family apartments, it is possible to start with them directly.
A few common strategies are: Cashflow Focused Buy and Hold- Buying a property that is rent ready or near rent ready with a focus on obtaining a good cash flow.
Getting a loan on an investment property can be a bit different than a mortgage on your primary residence.
Note I did not say real estate agent here. When finding a primary residence, your search may begin and end with a real estate agent. However, when looking for an investment property, more options are to consider.
When purchasing your first investment property, deciding whether to hire a property manager or self-manage is a significant decision. There are pros and cons for both sides here. In the end, it will depend on how active of a role you want to play in managing your investment.