I find metta meditation, or metta-like meditation, to be a very reliable way to induce piti. Now, pretty much as soon as I sit down, even before I start trying to meditate, happiness & piti start to arise. This is after about 1-2 months of practice. I've been using
instructions at Ron Crouch's website for "classic" metta as a guideline, while allowing myself to experiment.
There is a lot to explore in metta meditation. Different thoughts (e.g. friendliness, good will, care & concern, love, sympathetic joy, ...) often give rise to different feelings. I've noticed piti, sukha, and metta all as distinct feelings that can come up, all well before I get near jhana. I'm just starting to explore the interaction of this practice with the hindrances.
One thing I've been doing is just creating piti and sitting with it, stabilizing it, developing it, and enjoying it, with the thought of reinforcing the neural pathways or channels which allow me to experience happiness. The Buddha
instructs:
Then you should train yourself thus: 'Good-will, as my awareness-release, will be developed, pursued, handed the reins and taken as a basis, given a grounding, steadied, consolidated, & well-undertaken.'
I've noticed my behavior change a bit from this, in that I've found myself being friendlier to people, approaching more. There is one person around which I've had some dislike for (simply due to his personality) and one night I simply started interacting with him in a friendly manner, without having to force it. I've also notice a few people seem happier to interact with me these days.
However, piti is kind of a rough, gross form of happiness. It's a bit edgy, even tiring at times. I'm finding I can experience it simultaneously with negative emotions. It's not peace. Compared to depression, or sensual addictions, it's a big improvement. Compared to the PCE (or at least the experiences I've had which seem to resemble PCEs), it's not so great. But I think it's been useful, and will still be for a while.