how do you financially support yourself during start up?

Move into your parents house. You gotta scrap and claw until you get enough traction to either:

1. get funded; or
2. cover your costs

Most of us have been there before, there is no shame.

Honestly, I would do what I have to do (legally)to pull through. I was in the same tough situation 5 years ago during my first startup. I moved into my car and called it home for some 6 months. This in turn allowed me to self fund the startup and get it off the ground entirely on my own. Later on when things became viable and looked like a business was emerging, it became a lot easier to talk to people and convince them to lend some cash.

Frankly speaking I am glad it went down the way it did. It was the greatest and most valuable lesson learned up to that point in my life. Do what you have to do. Be honorable and always see a glass half full where doubters tend to discount you. Hope this helps.

Find a new, rich spouse? ;)

I would think "working all week long all day on the product" and "freelancing jobs" are almost mutually exclusive. However, you can try the freelancing sites like GetAFreelancer or ELance and find something there.

Your other option is to find a part-time job that won't leave you tired but give you enough to make the essentials.

Becoming a "professional mooch" is not the answer. Quite frankly, there's almost as much work there as not.

One important question: Do you have a business plan of some sort? Can you show someone how much and for how long you'll be in the red if you worked at it non-stop? Any investor, from family and friends to a real investor would want to see your numbers. But, most importantly, you should have those numbers for yourself. You are investing in yourself and you owe it to yourself to have this organized, and to know when to cut your losses.

I'd only take the option of moving in with your parents if they are absolutely clear that it's a business choice, and will require as much of their co-operation as your own. If you can do this professionally, you will want to save every penny you can.

Personally, I have a family to take care of with fairly high expenses, so my business model has to include a a strong enough revenue stream to continue life early on. So, having said that, here is my rough plan (and it's been working great the past 6 months):

1. Take on client work as much as it takes to pay the bills
2. In the 20-40% spare time from that, develop products
3. Transition away from contract work as product builds traction

Balancing freelance work (in my base, through the startup) and product development can be very tough and requires a lot of discipline. If you haven't freelanced much before, this may not be a viable option (way too distracting from your core goals).

Bottom line: reduce your costs wherever possible! If this means living with your parents, or in your car, or cutting TV, etc. do it! Make the sacrifices to make it happen.