You just take the usual and sensible precautions and you'll be fine.
Utila is the most economical island and has plenty of low budget well maintained accommodation for $10-25 per night, plus restaurants and shopping is cheap.
There's a couple of small cayes for rent, about $100 per night, and dive schools that give personalised instruction.
I hope this helps and PM me for further information.
Warm regards,
Andy