Companies need to be incorporated and founder stock must be issued before executing a SAFE and taking any investment. There should be some time between issuing/paying for founder stock and receiving the investment, to ensure the founder stock purchased was at the correct price (rather than at the price the investors paid) as this is a potential tax issue.
They first step is to nail down a lead investor. They will set the terms for the rest of the round (usually everyone participating in the round gets the same terms to keep things fair).
You should share a high-level plan for how much you are looking to raise. Most investors will expect that you will give up 20% or less for a round so you shouldn’t low-ball yourself by saying you are raising X amount at Y percent.
If they are ready to commit, a lead investor will offer a term sheet (usually for a SAFE convertible note) for the largest amount of the total round. You negotiate terms (there’s really only a few terms in SAFEs) and then their lawyers send you a SAFE to review with your lawyers before signing. The money gets wired to your bank account on a funding date.
After closing the lead investor they help you fill out the rest of the round by providing introductions (angel investors, other funds), but it’s probably better to find angel investors yourself with people of strategic importance or have contacts in a specific industry (angels have incentive to help you and, since there is an abundance of angels, you might as well get the additional benefit of expertise).