You mentioned "projects" (plural) and the way I have it setup is pretty similar to those recommending an LLC (or S-Corp) in CA.
While the annual cost of $800 minimum tax plus maybe another $500 in administrative fees (accountants, legal, etc.) is real money spent, you can make it back in tax deductions and potential liability. If you have a structure in place (another entity that is not you personally), it is much easier to deduct expenses (less red flags) IF you make an attempt to actually generate income -- the government cannot stop you from being a bad business person :)
If you are in a 50% tax bracket, this could easily be offset by $3000 in expenses such as hosting fees, domain names, costco membership, cell phone, even your car lease. If you are renting, you can possibly deduct some portion (~20%) of your rent (do not do this if you own a house). Get a separate bank account + debit card, a separate credit card (maybe a business one with rewards) and pay everything using that entity. You will end up making "owner contribution" from your personal bank account to your business account every month.
The extra wrinkle if you have multiple projects is that you can further separate your different projects into "DBA"s (Doing Business As) which costs an extra $100/yr (County Clerk Recorder, Publish in Magazine, separate bank account, credit card, domain name) 100% owned by your LLC (or S-Corp). If you shut down a DBA, it will cost maybe another $50. You will need a DBA to open a bank account under that name.
While this may look like overkill, this keeps everything clean and if your side project does take off, you will have some history with the business.
On a day-to-day basis, what I usually end up doing is setting aside a day to deal with all these entities. Most bills are on each "company" credit card and I call all the credit card companies to align the closing date. For example, all my credit cards close around the 22nd or 23rd of every month. On the 12th of every month, I pull up each account and pay them all using one screen of online billpay if you have all your business accounts tied together using your SSN.
Note: I have other companies that are their own entity as they are generating income & have other partners. The setup here is specifically just for my side projects.