White to invade at the 3-3 point, as the black extensions on both sides are narrow.
C[FORCE Please play at 'A' to start.];W[qq];B[qp]
C[NB. If black had played 'O2' here, white could reply...... i) 'P4' if 'L3' is strong (see 2701)......ii) 'O3' if 'L3' is weak (giving up the corner, and attacking the lower side).]
C[RIGHT White has made territory, caused black to overconcentrate his forces, and kept sente. However, because black has made great thickness, proper timing of the 3-3 point play is required.])))