You generally need to add
something to thin the juice some. My VG juices are generally 10% vodka (80 or 100 proof). Some use pure grain alcohol (PGA), but I can't get that in PA. Water works too, and I am now exploring this as I don't want to necessarily be vaping ethanol all the time!

YMMV, but 10-20%
distilled water is a common amount. This all depends on how much flavor you use too, as flavors are generally a mix of flavor compounds, PG and/or alcohol, so if you make a 30% flavor VG juice, you may not need to add anything.
And, yes, just VG and 10% flavor may clog the atty and keep the juice from wicking properly to the bridge. I killed a few attys in the beginning before I started thinning. Clogs will force the atty to run too hot and shorten its life, not to mention sometimes the clogs cannot be cleansed out.