@Ian Ray - Start with underwriting the deals . At a really high level you will want to model current performance vs. future performance, what it will take to get to the future and how you will get there.
In today's multifamily world, most are looking for the value add deal. Where do we spend money in order to increase rents and how can expenses be trimmed. Maybe it's through interior improvements or exterior upgrades. Maybe you're reducing expense by submetering water or implementing a RUBS program. There are a lot of different ways to approach it.
Once you figure out the business plan, the next step is determining how you're going to fund it. You can get a loan to cover a lot of the cost, but you will still need equity for the down payment, closing costs and often times repair/upgrade costs. This is where syndication comes in. If your underwriting and business plan shows you can drive rents and improve NOI, you can raise money from investors looking for a return. You get a percentage of the cash flow and so do they. Everyone wins.
Generally investors want IRR of 13%+ and average cash on cash return over 9%. But all investors are different so that's not written in stone.
Hopefully that helps with some direction. Happy to assist further if you have more questions.
@Tony Robinson - similar here, although on a 6 unit it's probably harder to syndicate and you're looking more for a partner. You do the work, they provide the cash and you split the deal 50/50, 40/60, whatever you can get them to agree to. Start by underwriting it and then solve for your investors returns. If it's 10/90 (you only get 10% of the deal) in order to get your money partner a decent return, it may not be worth the effort.