I won’t spend a great deal of time on any one of these items, but I think I’d be remiss to ignore them completely.

Holy Water -
Catholics and non-Catholics alike sometimes use holy water as protection from spirits and evil entities.  It can
be carried on an investigation or in dire circumstances cast in entryways orwindows.  It is also used to anoint candles, crosses, other items and occasionally people as well.

Charms, Amulets, Tokens & Talisman –
These include crosses, holy medals like St. Michael, crystal quartz or silver jewelry.  Anything with spiritual
or sentimental meaning has been used for this purpose.  They may be worn or similar to holy water they can be placed in locations where negative energy resides.

Garlic –
Believe it or not it is still occasionally hung over doors.  I have personal knowledge of someone who carries a clove on each investigation.

Energy Stones –
In my experience the most commonly used crystals are quartz, black obsidian and black tourmaline.  They are
occasionally recharged by placed outside, overnight on a full moon or by allowing a loved one to hold them. 
You should never allow anyone with negative energy to handle your stones.

White Candles -
White candles are said by some to symbolize positive energy.