Here are 2 things that work for me....
1.) put water in the roasting pan and turn the roast a couple of times during the baking time. I also add water as it steams away.
2.) get those Reynolds cooking bags. I've used the recipe on the box, adding a touch of flour, a packet of the onion cup-a-soup mix and then tie it shut. DON"T Forget to poke a few holes in the bag BEFORE putting it in the oven!! I found out that the hard way

I cook it according to the box and it comes out nice and moist every time. The bags come in dif. sizes so that helps alot!!!

from me!!
Hope that helps.
I also will cook a roast on the stovetop. Place it in a big pot, add water, cut up veggies and 2 beef bulion cubes and 1 chicken bulion cube. Cook on Med. high heat, turning roast a couple of times and adding water as needed. Cook until a meat thermometer registers 160 F or higher. ( get thermometer closest to the center of the roast for accurate temps

) Sometimes I'll cook the roast for abit, then add the veggies.
Hope this helps, too!
Peace!

Nancy S.