What do you first introduce as puree for your LO when starting solids and why? Which foods do you mix your BM with and which do you not?

A lot of my friends started with apple, pumpkin or sweet potato as puree. These are slightly sweet in nature and easier for baby to take to. As for mixing in breast milk, I've heard of friends who uses breast milk for cereals. One tip from a friend is to store smaller amounts of breast milk in baby food jars/bottle so that you can easily warm one bottle instead of having to warm a full size milk bottle for a small amount of breast milk for the meal. :)