  The Kepler, K2, and Transiting Exoplanet Survey Satellite (TESS) missions
have provided a wealth of confirmed exoplanets, benefiting from a huge effort
from the planet-hunting and follow-up community. With careful systematics
mitigation, these missions provide precise photometric time series, which
enable detection of transiting exoplanet signals. However, exoplanet hunting
can be confounded by several factors, including instrumental noise, search
biases, and host star variability. In this Letter, we discuss strategies to
overcome these challenges using newly emerging techniques and tools. We
demonstrate the power of new, fast open-source community tools (e.g.,
lightkurve, starry, celerite, exoplanet), and discuss four high signal-to-noise
ratio (S/N) exoplanets that showcase specific challenges present in planet
detection: K2-43c, K2-168c, K2-198c, and K2-198d. These planets have been
undetected in several large K2 planet searches, despite having transit signals
with S/N > 10. Two of the planets discussed here are new discoveries. In this
work we confirm all four as true planets. Alongside these planet systems, we
discuss three key challenges in finding small transiting exoplanets. The aim of
this Letter is to help new researchers understand where planet detection
efficiency gains can be made, and to encourage the continued use of K2 archive
data. The considerations presented in this Letter are equally applicable to
Kepler, K2, and TESS, and the tools discussed here are available for the
community to apply to improve exoplanet discovery and fitting.
