Sorry, to clarify, we are talking about your first solo IMC flight and not inadvertant IMC entry? If you are embarking on your first, planned IMC solo flight you should have
1. The required IF rating on type.
2. An aircraft certified to operate SPIFR.
3. The requisite currency required to maintain your SPIFR rating.
4. The required confidence in your own IF experience to embark on a solo IMC Flight.
If we are talking about inadvertant IMC entry in a machine or in WAT conditions unsuitable to IF flight, well that is a different kettle of monkeys.