How Can I Help My Dog Be More Secure?

[Someone Going Somewhere]

So, I have a 10yr old border collie/lab mix. I don't often take her there, but she enjoys going to the dog park every now and then so I indulge her once every month or so. I just find that its full of high-energy dogs and my girl likes her personal space- dogs there tend to be very aggressive when it comes to sniffing and whatnot and it makes her nervous. I realize its my fault that she isn't comfortable around high-energy dogs, so I'm trying to find out ways where I can make her more comfortable in those social settings.
Usually she's fine and she likes to play chase with the other dogs but then the occasional dog presses her personal space too much and she gets into a barking fit. She's a medium sized dog, so I get a little concerned when these larger dogs start getting into it with her. I guess my questions are,
1. How can I make her more comfortable in these situations?
2. Does her insecurity make her a target?
3. Last but not least, should I just avoid the dog park altogether?
I'd hate to do it since she loves being off leash so much, but I feel like people with high-energy, poorly trained dogs just let them gather there and do whatever. Tonight, a poodle was being very aggressive and the woman didn't even call her dog off when she was growling at mine. Maybe its just better off to only take her on days when there aren't any other dogs?