Pests build up unnoticed for a simple reason: most owners look at the tops of leaves and stop there. Pests prefer the places nobody checks, so a plant can look fine from above while trouble gathers underneath.
Inspect new plants first
Start with any new plant before it joins the rest of your collection. Check it over, keep it apart for a while, and watch it before placing it next to your other plants. A new plant is the most common way pests arrive, so that first check does the most work.
Check the places pests hide
On a regular routine, check leaf undersides, the joints where leaves meet stems, and the soil surface. Look for tiny insects, fine webbing, sticky residue, or leaves that look speckled or distorted. Early signs vary, and identification from one symptom alone is uncertain, so treat anything unusual as a reason to look closer, not as a final verdict.
Isolate and clean up
If a plant shows signs, isolate it from your other plants right away, so the problem stays with one plant instead of spreading across the shelf. Wiping leaves is a good first step, and it also gives you a closer look at what you are dealing with. Remove dead leaves from the soil surface, and keep checking moisture, since soil that stays wet invites its own problems.
Inspection is a habit, not a one time event. A quick check on a regular routine, wherever you call home, is what catches pests while they are still a small problem.