tox screen, alcohol level
fingerstick glucose
drug levels as indicated (ex. antiepileptic level if possible ingestion)
Head CT if concern for trauma or mass lesion
Lumbar Puncture in most cases unless etiology is known
EEG if possibly seizure related
Ataxia 
Systemic conditions
Dysphonia
Intoxications with diminished alertness
Dysphagia
Ethanol
Diplopia
Sedative/hypnotic toxicity