If I were you, I'd pick an established recipe and brew that. If you get a beer, using a personal recipe, that you don't care for, you won't know if it's your process or the recipe.
I brewed three extract batches before I switched to all-grain. It took me three brews of all-grain to get the process down, at least to where I am brewing nice drinkable beer. Learning a number of things, from preheating the mash tun (if you have a cooler setup) to how to adjust mash PH to how to sparge--well, looks simple on paper, but when you're standing there and your mash is under temp and you don't know what to do....
My first batch, I sort of kinda in a way tried to fly sparge. Big mistake. I also didn't stir the mash during the hour it was in the tun. And I was short on the wort collected so I was adding additional sparge water out of bottled water.
The result was....ok. Not something I was willing to bottle and give to others.
My 3rd all-grain batch, I got the temperature thing figured out, amended my water (I'm using RO for most of it), mixed the mash during conversion, had much higher efficiency. And the result was the first beer I'd have paid money for.
Anyway, enough said--unless you've watched someone do all-grain and have a good handle on the process, IMO you should consider brewing an established recipe.