I find it's helpful to take a deep breath and hold it while searching for just the right spot and speed of stimulation. It takes you closer to the edge and makes it possible to achieve the powerful ecstatic soul-quenching anxiety-relieving melting sensation that is accompanied by clitoral and vaginal throbbing during cllmax.
I also find it's helpful to place my attention on what I am doing, paying attention to where and how I'm stimulating myself. You will notice there is one spot that is more sensitive than the surrounding area. Very, very gently tease that spot by going nearer and nearer. At some point you will be able to touch it and melt into an cllmax.