I fly out of LaGuardia on a pretty regular basis. Security is tight insofar as you have to take off your coat, take your laptop out of the bag if you have one, put your coat, computer, all carryon bags into the scanner, walk thru the metal detector. Provided it doesn't go off, you just have to take your shoes off and they search those. Then you're free to go. If you set off a metal detector, they search you with one of those detector wands. If you are planning on bringing substances, I would suggest packing them carefully in your non-carry on luggage because I have had my carry-ons searched at random numerous times - they will pull all the stuff out one by one. That happened to me at the search counter but they also do it randomly at boarding too. So just put it in your checked baggage, they x-ray that but that's all usually unless there's something suspicious in it.