Nice decision! I don't think you should be too concerned with upvoting too much. When your SP is low, it doesn't matter if your vp is 100% or 20%, the value of it will still be <$0.01 and makes no difference to the author. Instead, it is your upvote and support that encourages the author.
So, keep upvoting! Of course, don't go upvoting garbage contents like memes, etc. LOL
Thanks @jrvacation. I've managed to increase payout by 1 cent in the past but it's hardly ever more than that and yes most times I upvote and I see no change in the payout value.