The most important thing is experience. As you travel, you will develop a process/ methodology for looking at how far you are going, what type of place you want to stop and what are critical factors for you.
No database, guide, app is perfect for picking RV parks. Even reviews from other RVers have to be taken with a grain of salt.
I'm of the pre-planning mindset. Nothing better to do on a lazy day than look at Microsoft Streets and Trips and plan out potential trips. But when actually on the road, I'm often distracted by a brochure, road sign, wife's suggestion and we don't end up where we planned to be for the night.
We've gotten pretty good at finding a place for the night, or a few days. One thing, I do research the area/ potential route. And make sure that I have an idea what is available in the area and alternates.
Too often while traveling, an app or phone is useless. Of the apps available, I like Allstays. RVParky is just too short on information where we've traveled, and too hard to sort quickly. I also must have something my wife can use with little 'expertise'. Otherwise, I would have to stop and do it myself.
Try them all, find what feels comfortable. Get some experience. You will find the right one.
Full-Time 2014 - ????
โNot all who wander are lost.โ
"You were supposed to turn back at the last street."
2012 Ram 2500 Mega Cab
2014 Flagstaff 832IKBS TT