Hi,
Went a few years years ago for 2 weeks to visit friends who were travelling. We all stopped taking malaria tablets because it is 'almost' unheard of in Goa, or at least it was at the time!.
VERY hot, you can tell the new arrivals cos they're white not brown. Bit strange being offered xmas tree baubles while roasting hot on a beach.
If you go to Anjuna market buy a drum from the FIRST person who offers you one otherwise you WILL be pestered ALL day, i guarantee it.
Buy loads of saffron to bring back as pressies for anyone who likes to cook. It is ridiculously cheap and they will love you forever or bring some back and sell it. You can make loads from the local restaurants.
It will be difficult but don't give money to the beggars. Firstly a lot of them get buses into the towns to beg, so it's almost a profession, and secondly they will follow you round every time they see you again. You have to be firm as they will, literally, be hanging off your arm.
Lastly, don't forget to haggle. Any price you see is not the real one. Cut your 1st offer to a third of the asking and don't go over half the original price.
Enjoy ya holiday