Place strawberries and tequila in large jar. Allow to steep for 3-6 days. Strain and bottle.
If you're planning on mixing (e.g. in margaritas), use a silver tequila, that is not too pricey (e.g. El Jimador or Espolon blanco).
If you're planning on sipping, use a decent reposado (e.g. Camarena)--the infusion will wipe out some subtleties, so it's not worth using a high-end anejo.