There are so many variations of wind-and-weather factors that I dunno if there are any hard and fast rules, but tarp camping is a lot of fun. The short answer is: yes, do a good job with site selection. Tarping is nice because it makes you think about where you are and what you can use passively to help yourself. Trying to answer you I’m realizing that most of my tarp knowledge is geared around increasing warmth and shelter. But I really like tarps and here are some things to keep in mind –
– at some point, you will get wet.
-air rolls downhill as it cools. So the bottom of a valley at night will be a few degrees cooler than, say, halfway up the valley sides, all other factors equal. (So a tarp side facing uphill is effectively a windblock, if it’s tight to the ground.)
-big rocks, cliff faces, earth berms, etc are heat sinks, and can retain warmth and be good windbreaks.
-learn your knots! slipped tautline hitches (or a few inches of shock cord on each tie-out) will keep your silnylong taut or easily made so. The Evenk hitch is a three-second ridgeline knot.
-bugs tend to be worse in the evening than through the night.
-all sorts of animals are active through the night, but if they’re making enough noise for you to hear, they’re not interested in you.
I have a UL bivy that I really like, it’s great in shoulder seasons and in winter, but in July and August in humid weather it is a sweatbath. If bugs are bad enough, that’s the lesser of two evils, though. I’ve seen a few custom bivies with a strip of netting all the way down the middle on BPL, those seem like a neat option. I like a bivy for a) a windbreak in cold weather b) keeping windblown rain off my quilt c) bugs off.
Depending if you use a ridgeline or your hiking poles or custom poles or some other way to set up your tarp, you can probably engineer a few hacks based on whatever system you use. (I hang bivy bugnet, glasses and headlamp from my ridgeline at night, and my sleep gear over it in the mornings to air/dry it out, and make sure its all there, for instance.)