My Dear Claire,
Thank you very much for your letter.
Visualize Guru Shakyamuni Buddha on the tip of your nose, the size of your little fingernail or a grain. Do this visualization with your eyes open, understanding that the object of visualization is an object of the mind (mental consciousness) and not the eye consciousness.
In Liberation in the Palm of Your Hand the advice on calm abiding is very clear, also in Lama Tsongkhapa’s Lam-Rim.
With love and prayer...