The prep advice on this forum is very good and I recommend you use it to learn what will work for you. You do not have to DE shave first, but it is a great way to learn. For example, as I recall when I shaved with cartridges, I used some pressure to get a close shave. I had to unlearn this when I began DE shaving. It's hard to understand how little pressure (some would call it no pressure at all) you need until you actually use a blade razor. I felt it gave me a leg up when I began exploring straights. DE shaving is not expensive (unless you develop one or more acquisition disorders) . You'll learn that blades vary greatly and that what works for others may not work for you. Same with DE razors and straights. All this experience is applicable to shaving with straights. All I am suggesting is that shaving with a cart or disposable is in no way the same thing as shaving with a blade, be it in a DE or a straight. You have to physically (develop muscle memory) learn how to do it.

Also, you will need a brush, a soap and/or cream, a lathering bowl (unless you face or hand lather), etc. to straight shave. The DE razor and blade are the only difference. DE blades are cheap especially compared to carts and a good starter razor can be had for around $30. I would be surprised if many of the straight shavers on this forum did not also have a DE they use now and again.