One of the easiest ways to start is to follow a ready-made template. You can find many of these in craft shops, but following the lines of a garment you already own can also work. A simple sleeveless tunic/dress is great to start with because it will usually be made up of either 2 or 3 large rectangular pieces of fabric which only need to be hemmed and sewn together.
Before the summer holidays started, my mum decided she wanted to have a go at making me a tunic to take on holiday. Below is a brief chart of her efforts:
Fabric, measuring tape and pins to get started
Close up of the pattern
We used a ready-made dress as a template; this one had two panels
of fabric at the back, one at the front, and a ruched hem
Close-up of the neckline
Hopefully that's inspired you to try out your own projects; if any readers have any they'd like to share, do send them in!