Sarah, It can be done, but as someone has already said it is harder. And as previously said it will depend on the nature of the business. If you need investment, it does not really matter which route or routes you go down you will need a solid business case that shows that there is potential to generate the cash and hence profit.
I personally always favour going down the company route it does afford you more protection.
I would always advice everyone to keep costs as low as possible even in good times. But when starting from a negative position it will be critical.
For example I use Skype (this is not an endorsement, these are alternatives) this saves on line rental. I have a skype link on my web site so if people use skype they can call for free. I use pay as you go conference facilities, and free software such as open office.
If you are looking for a host for a web site, make sure you choose one that gives good value. I swapped this year and am saving myself 00's of pounds and getting more for my money.
Will your business allow you to charge some or all up front to help cash flow. If you are supplying product can you keep stock down by frequent orders. I use a supplier, I have samples and if I ask, they will have the stiff with me next day. It saves in carrying stock.
I'm sure there is a lot of advice you can get, I have found those in business and successful in what they do are the best source of advice. So join what ever groups are in your area.
I hope this helps. One other point - you need to be quite dispaaionate, logical and hardheaded about this, what ever you do needs to be well thoughtout.
I would strongly suggest getting some solid professional advice.