I find that strengthening the triceps is very relative for progression on pressing movements for most women. A little bit of added focus can make a pretty significant difference IMO. Another thing to note is joint health; specifically wrists, elbows and shoulders. They seem to be a common problem area, in my experiences, and this holds significantly more common on naturally skinny women.
Just something to keep an eye on. Make sure all the movements are clean, wrists aren't rolled back on bench or pressing, elbows follow proper lines, etc..
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