Most people say HELOC, but assuming you can't do that you could try to get cash out on your auto, use secured and unsecured business credit cards. What you do is set up a holding company that is a separate LLC then rather than do cash advances you just do normal transactions. You want to do one that has a low monthly fee and a low fixed fee of under $1 per transaction. If you go with the ones that are 1-3% per transaction thats not really a good deal. There's prob other products out there if you just do some research. I haven't personally done this but Juan Pablo on youtube has used this method to get several units. If you can't get a commercial deal use this method to put 3% down on a residential deal or a 4 plex and do house hacking or vacation rental.
Next you can use the cashflow to get more residential properties. Once you have 4 residential properties you can get up to 100% LTV on equity lines of credit to fund your commerical deals.
Some people recommend selling your deals and doing the 1031 exchange. Personally I'd rather just get equity out and continue to collect cashflow on the residential deals, pay off the equity lines and continue to get more deals etc.