I too live in Marin, and feel it is a solid long term market for apprecaition, and utilizing the power of principle reduction.When it comes to refinancing, figure out what the loan costs will be, then divide that buy the monthly savings with the new loan in order to determine how long you have to maintain that loan to break even. 

To thrive in real estate investing, you must maintain a firm grip on your finances.

You need to maintain a fund to handle those unforeseen expenses

I understand that starting out, depending on how fast you want to build your portfolio, you could spend a lot of time at it.For those with established investment portfolios, how much time is required to maintain it?

Ensure separate bank accounts for the LLC, and maintain proper formalities to avoid liability issues.

Ensure your flip profits exceed the LOC costs, maintain a financial buffer, and compare it to private or hard money loans.

You should ensure the property is inspected regularly, maintain climate control to manage moisture and temperature, and address small issues like leaks or cracks early to prevent costly repairs.

I intentionally minimize my cash flow (try to maintain high LTV, use accelerated depreciation to our advantage, etc) because it gets taxed annually.  

To thrive in real estate investing, you must maintain a firm grip on your finances.

Those are repairs that we had to pay for, however, and that can cut into your cash flow if these problems occur often.Well maintained equipment is also key.