I would agree that a mixture of pre-tax and post-tax accounts would be good to have.
If your employer has retirement accounts to participate in, that is a great place to start.
However, if also have to have accessible savings. Some very liquid (that you can reach in hours or a day or so), some maybe not so liquid. You should have emergency savings in case of loss of job, car breaks down or you have some other major repair or financial emergency. Having some savings to cover those things is great so that you don't have to borrow (or might not be even able to borrow) when the need arises.
After tax savings might be forms of mutual funds, interest bearing accounts, stocks, bonds, etc. etc. There are many choices to consider. Part of which is based on your knowledge and tolerance of risk.
But in any event, you have to start somewhere, and a savings account earning the highest rate of interest is a good place to start. Check banks, credit unions, and online banking (check web sites that show institutions paying the highest rates of returns and types of accounts.) Good luck