1790-1840 Censuses only list the head of the household, but don't overlook using them. They are helpful to place a family in specific locations at specific times.
When the head of the household is no longer listed, don't assume he/she is dead. It's possible that the former head of household is now living with one of the children.
There are three types of wills: Attested, Holographic and Nuncupative. The attested will is the most common and is prepared for the testator. A holographic will is written by the testator himself. A nuncupative will is the deathbed wishes of the testator, recorded by a witness present at the bedside. All wills must be witnessed.
Marriage Records may only be records of the wedding. However, you may also find the Application for Marriage completed by the bride and groom-to-be. Marriage records may also be corroborated with church records. Check everything for correctness. There could also be a newspaper account of the wedding.
Probate records refer to wills, inventories, letters of administration and guardianship. They are usually held at the county courthouse unless archived and they are indexed by the name of the testator.