Ok Ski here are a few tips. Get cheap bright neon plastic no trespassing signs. Expensive ones will be pulled up ,shot or destroyed.

Adults can read and are charged with knowing the law so special words are not needed. For them NO Trespassing or Keep out etc, signs are good enough. Post a few along obvious places up on trees 9-10 feet in the air but easily visible (hard to tear down) then a few lower so kids can see them.

Kids don't read and are not charged with knowing the law so words on signs don't matter but skull and cross bones signs ( with the words danger keep out ) like on hazardous chemicals are good. It is the attractive nuisance of a pond or water or equipment that gets you wrt kids. Barriers are what you need for kids. Any where you think they may come on the place post a sign and block the trail (not with a neck high wire that may get someone on a bike or 4-wheeler) but some thing substantial and visible. Remove , take down or make inoperable any thing a kid may play on (swings , bars , equipment , power, etc.). Put a gate on the pier so no one can walk out on it with out opening the gate (lock it). For the pond have a few signs that say no swimming , diving , fishing or boating. Put one on the locked gate facing shore. Put one near the beach. Others as needed. On a post out in the water is good if the ice won't cause a problem.

Tell your neighbors to stay out unless invited if that is what you want. If you tell one person it is ok to come on then everyone else will say when confronted " ole Bill who you let come on said it was ok if we did".

Rule 1 about trespassers , first take his picture from way off or have one from a hidden trail camera then call the law. Rule 1A if you are going to confront them (which I do not suggest) do it on your property and when you have them out gunned and have the drop on them. Better if you have back up help that is well armed and at a safe distance with a clear shot with you out of the way. Distance is the first line of protection don't get close and don't give them a chance to harm you. Having said this a word of wisdom is warranted. Think about this WRT your plans. The guy you throw off can easily come back and burn down the woods or house or poison the pond. You have a lot to lose and he may not.