The following list and diagram are from Module 10: Conversation and Lexis - A Course for Assessing and Developing Lexical Competence on the Internet.
Features of authentic speech such as:
10.1. Filled pauses: Sounds such as er, um, erm, etc. give speakers time to think.
10.2. Fillers: Words such as "well, you know, I mean" which carry no meaning but give speaker time to plan what to say.
10.3. False starts: Speaker starts in a particular way, then changes their mind and begins again.
10.4. Repetitions: Same word or phrases said repeatedly.
10.5. Contracted forms. In addition to verbal contractions, some words are shortened: "Them= em"/because = cause".
10.6. Ellipsis. Pronouns or relatives are omitted.
10.7. Non-standard grammar. They break standard rules.
10.8. Hesitations or silent pauses.
All these features have been compiled in the following diagram
All the best.