I do lots of stews in mine.
Saute chopped onions with leeks/celery etc. then add to slow cooker.
Chop lamb/beef into bite sized pieces (don't use supermarket marked, "stewing" meat - it's always awful. Use lamb shoulder or beef shin or similar). Season and dredge in flour then fry in batches and add to slow cooker.
Add chunks of preferred veg - we like carrots/butternut but parsnips, potatoes, etc all work well.
In pan used to brown meat, add some wine, tin of chopped tomato or passata, a stock cube and enough boiling water to melt stock cube. Bubble for a few minutes then add to slow cooker. Top up with water from kettle to just cover.
Flavourings:
For beef, I tend to keep it simple, adding ginger to the onion mix, salt and pepper and a bay leaf. You could add a clove or two as well.
For lamb, we like a stick of cinnamon and a star anise with a squeeze of honey. Alternatively, a half teaspoon each of cinnamon, cumin and coriander, added to the onion when it's translucent can be nice. A teaspoon of sugar/some honey if desired.
Cook on high for 4-5 hours or low for 8-10.