Lacking a stud finder, you can generally see the fasteners that hold
the siding to the studs. That should find the studs, but there are
other considerations such as; wires and pipes. Frankly you never know
when you drill, but you can up your odds by surveying the site and
noting infrastructure in the area. I've been drilling with little care
to the above for 30+ years, and have yet to hit a pipe, and only grazed
a few wires. Just go slow as you break through and feel with the drill,
may the force be with you.