In Portland, am apt broker and have worked with builders on land to units.
First, you'll need to get money. Const can range from expensive (in good markets) to more expensive (overbuilt or lower rent markets) to ludicrous (hard money.) Bonus points if the lender can do const finance and then final occupied financing.
To get that, you'll need:
1) Figure zoning out and how many you can or want to build
2) Go to architect and builder and get a sway on layout and costs
3) Most painful, go to the governing entity for permits and pay your soft costs. In Portland, this is getting close to $25K/unit.
4) Get a timeline from your builder and make sure he can serve as a gen contractor to get all jobs done on schedule, THe longer it takes the more debt you incur.
5) Start building from site improvements (grading, utilities), then foundations to finish. Each step means a guy from city coming by. If your GC is on their good side, so much the better. Inspectors can f*** you up without too much effort.
6) Start lease up ASAP. You're going to need to be full before a bank will give you cheaper final financing.