Relax... maybe sewing relaxes you, but if you find your frustration increasing, if you start hurling colorful language at inanimate objects, then take a break. Walk, have a snack, start a load of laundry, rake some leaves. I've never had happy results trying to push through on a sewing project when I am confused, tired, hungry, cranky, stressed or too distracted. And it pays to remember that the sewing can wait, and it will be a happier and more successful process when I feel calm.
Take the challenge that gets you excited... sure, it helps to learn basics on fabric scraps and straight lines, but don't deny yourself the challenge of making something you are going to enjoy, something that you actually want. Napkins and patchwork are good beginning projects. A vest... well, it's not easy, but taking our time, accepting help, keeping our humor, and having our seam ripper handy, we will learn a lot, and have something good to appreciate for our effort. There's no shame in making mistakes... we just have to try again.
But wait... first I will sit with the chickens, brush the goats, breath.