I don't know if I can come up with 10 tips, but here are a few off the top of my head.
Make sure you have enough land for the animals- not enough land in summer, but enough in winter. The ratio is 4 sheep an acre, I think, but if your land isn't good, prone to flooding in winter, that can reduce the usable amount considerably in winter. Ideally you want enough so that some areas can be rested too so that you can move animals around and onto a fresh field.
Consider the soil type, wish I'd done this more when we bought here- we are on heavy clay, and it is quite wet in winter, despite the fact that we are at the top of a rise.
Water/ electric- electric is useful, but I would say water is essential. I know some people do cart water to their land, but that must be tough.
A building or buildings would useful too, even just for storing hay etc in, even if there is not enough room to bring the livestock in poor weather.
Fencing- most important, that it either has good fencing, or that you can get good fencing put in. Either by yourself, or by a contractor if you have money available.
Hope that helps a little- I'm sure other people will mention other things too!
Beth