It's a pretty straightforward style. Keep OG low if you want to be true-to-style, there's a temptation to make it bigger.
Key points:
Malts are certainly the focus, with many using Maris Otter as the base. Certainly a good starting point, if nothing else. Pale chocolate and crystal malts are usually included. Consider brown malt as well if you really like a roasty flavor, as high as 15%. You can definitely obsess over the malts to good effect.
Mash high. 70C/158F is a good starting point. Especially if you let the temp sag over the mash, it's going to come out quite thin if you go too low.
Hops hardly matter, anything Fuggle-like will do.
Consider fermenting a bit high for some yeast character. I think this balances out the flavor a bit, lest the beer come out tasting like roasted-barley tea. Keep malts the focus, but I've done WLP002 at 63-64F for the first 4 days and felt that was a bit too low.
Most will find some time helps, letting it condition for a couple weeks or more. It can be a fun one to sample over time to track the difference.