I don't like adding flour to stews. I put cut-up potato in at the beginning, which thickens the stew nicely. I add more cut-up potato about half way through, which gives some nice potato bite. You can brown the meat if you like, but I don't think it makes much difference, and it mucks up the cooker, takes time and stinks out the house. Celery is fine if you like it. I don't add it to my stew for the simple reason that I've never done it.

I'm going to make a big batch of lamb stew this weekend, following, more or less, Gennaro Contaldo's Youtube version. I use frozen peas which I add near the end. I wouldn't add peas to the portion saved for the next day until I reheat it, as they go a bit sorry-looking if they've been in there all that time. It's a beauty, even though he breaks the Italian rule of not putting garlic and onion in the same dish. At least he doesn't mince the garlic...