There are dozens of Enneagram tests available online. Many people simply take the first test that appears in the Google search results (or whichever search engine is used).
The problem with that is just because a website is good at marketing its test on the Internet doesn't mean the test is any better than the rest. Good marketing skills don't necessarily equate to a good understanding of the Enneagram types.
In finding an Enneagram test, the first thing you need to decide is what you are expecting from it.
Finding your Enneagram type starts with determining which of the nine personality types best fits for you (your basic type). If you're just starting your exploration of the types then discovering your basic type is where to begin.
As you explore the Enneagram types deeper you'll likely want to look at the variations within your type. These variations are found in the concepts of wings, tri-center (gut type, heart type, head type), and instincts (subtype, stacking).
Many of the tests you'll find in the links below help you determine more than just one thing. In particular, tests that result in scores for all nine types can be used to derive not only basic type but variations of type as well.
In reality, you are all nine Enneagram types to varying degrees. It's just that one of those types will be more dominant or primary than the others.
Your basic type is the Enneagram type that best fits for you. While some people can find their basic type by simply reading descriptions of the nine types, others may have a more difficult time choosing between two or more types.
While basically you are one of nine Enneagram types, each of those Enneagram types has a number of variations.
Two variations of each type have to do with the influence from the adjacent types or wing types. After finding and exploring your basic type you may next want to explore your preferred or dominant wing for that type as well.
Another variation of your basic type resulting from the influence of other types can be found in the tri-center approach to the personality types.
The tri-center approach looks at your basic type plus two other types - one type from each of the three centers. You may see this approach commonly referred to as trifix or tritype (although those terms more correctly refer to two specific implementations of this approach by two separate schools of the Enneagram types).
Often referred to as survival instincts, the instincts are not found on the Enneagram symbol itself but overlaid upon the types or used independent of type.
Instinctual subtypes describe three variations of type based on the self-preservation, sexual, and social instincts. Instinctual variants look at a person's primary instinct with or without reference to type. Instinctual stacking looks at a person's preferential ordering of all three instincts