Stirring definitely helps. The exact setting to use will vary depending on the microwave, what is being heated, and how much of it there is, but my usual go-to for a starting point on a full, regular-sized bowl or plate of food is: 3 minutes at 40%, remove and stir or flip as appropriate, then another 2-3 minutes at 30-40% depending on how hot it was. This approach will end up heating most things evenly without drying them out or burning anything.

Some things can be more sensitive, so if I'm ever unsure about what would be safe, I'll start at 30% for 1 minute just to get a baseline for context. Below 30% is usually only useful for frozen things. Soups usually require several stirs - you don't want to let it sit still for too long, or use too high a setting, or it can explode.