Look beyond the plaster finish
Plaster may cover wood lath, metal lath, masonry or another backing system. Those differences affect both detection and attachment. The visible finish should not be treated as proof of a suitable structural fixing point.
Investigate before marking the bracket
Stud-finder readings can be more difficult to interpret through thick or irregular plaster and lath. Use a method appropriate to the construction and verify uncertain results. Do not assume framing locations from a nearby outlet or a standard spacing alone.
Protect the finish while following the mounting instructions
Older or damaged plaster can chip or crack during work. The appropriate drilling and fastening process depends on what is behind it and the condition of the wall. Avoid overtightening hardware to compensate for a poor fit or uneven surface.
Decide the cable finish
An in-wall route can be more involved where lath, blocking or other obstacles restrict access. A surface cable cover may offer a practical alternative. Discuss the appearance, the permitted openings and any patching expectations before work begins.
Information to provide
Send photos of the wall and any existing cracks or repairs, together with the TV and mount model numbers. Mention whether the building is rented or has restrictions on drilling. If an old mount remains, include it in the photos rather than assuming its fasteners can be reused.
The objective is a suitable structural attachment with a carefully planned finish. If the construction cannot be established confidently, resolve that uncertainty before making mounting holes.