I'll second the opinion and go ahead and say validate as much as you can.
Not validating classes in order to get "easy A's" doesn't always work out to your GPA's advantage. For instance, a number of people elected to not validate Composition (EN101) during Beast, myself included. Turns out it is very difficult to get an A in Composiiton even for bright plebes because many of the instructors grade you compared to your fellow classmates and a roundabout form of force distrbution is imposed through their methods. Plebe history is the same way as far as validation goes-- very tough to get an A because of a combination of the nature of the course.
Some classes you cannot validate, like Psychology (PL100). If you validated, you get put in advanced psychology and you dont get any free room in your 8 semester schedule that all of your classes are planned out on (your 8TAP).
Best advice I can give you on validation is to validate as much as you can for this reason: most validated classes free room in your 8TAP in your cow and firstie years. When someone validates history, they get put in Mil Art which is usually a firstie class. Validating plebe history gets you two semesters of free space firstie year for your major. here are the classes I recommend validating if you can:
If you validate history, math, IT, composition, chemistry, physics, or literature then you actually free up a semester or two on your 8TAP. Notice almost every class that you can validate is on this list.
These free semesters allow you to do a lot of neat things without like a semester abroad, a double major, or an honors thesis without overloading too much. From what I've seen a lot people who validate a few classes end up using this free space to take more classes for their major(s). In my limited firsthand experience from just finishing up plebe year, validation is definitely worth it.