Banking setupI use a credit union for checking. I'm currently planning to open up a second checking account with the same credit union to split my income stream into fixed and variable expenses as some have mentioned here.
General idea is as follows:
1) Deposit income check each month into checking account #1. Draw from this account for monthly and yearly expenses. Add some buffer so as not to over draw.
2) Initiate an auto-transfer from checking account #1 to checking account #2 after check is deposited each month. Work within the budget set by checking account #2 for variable expenses.
Why use a credit union? A for-profit bank does not share the same incentives as their clientele. If they can separate you from your money, they will. I'm generally wary of any industry that is rewarded financially for stealthily screwing their customers, e.g. insurance industry. Credit unions are also known for having very reasonable loan terms.
Why two checking accounts? It's nice to know what I'm spending each month on stuff like gym membership, streaming music, cellphone bill etc, versus things like coffee and dining out.
Investing setup
I'm young. I'm willing to incur risk for better long term returns (on average). I also recognize that I am not Rentec. If I were to outperform the S&P500 picking stocks, it would be almost entirely due to random chance.
I keep enough money in checking to survive an emergency that requires immediate access to funds. Everything else that I earn above what I need for the month goes straight into an S&P500 index fund. Both Vanguard and Fidelity are essentially fungible.
I'm open to others convincing me that this is a stupid strategy. It is entirely possible the S&P500 tanks, and I lose a large fraction of my money. Few counter points though. First, it is by definition a diversified portfolio of stocks. Second, it has performed very well historically. Third, it has enough people invested in it that it couldn't just "go away" without serious repercussions for the US and the world.
Perhaps the largest concern, is that there is way more wealth in the S&P than there are people actually trading it on a day by day basis. If there was a flash crash, there simply wouldn't be enough people on the buy side of the equation to drink from the firehose of people selling. This is really beyond my depth though so I'll stop here.
Other principles
I'm trying to avoid debt like the plague. Mostly for my mental health; I know it can be important to your credit score to carry some continual debt. Be wary what you sign up for (college, grad school, etc).
Keep in mind though, you always want to maximize your net effective interest rate. If your student loan rate is 4%, consider paying the minimum on your student loans and put the difference (what you would have paid) into the stock market. Only do this if you can automate the process as you will be inclined to spend the money and not save it.