For intaglia, (i.e, when knitting a pattern with a motif,) it's much easier if you just unwind lengths of yarn, about a metre, and leave them trailing at the back. Just gently pull the threads through when it begins to get a bit tangled, or after you have crossed the thread to prevent a hole appearing in the knitting.
Also, when knitting fairisle jerseys or anything basically tubular, it makes a big difference if you use circular needles so all the pattern is done on the right side, ie, the Knit side, the side you can see. If you knit the back and the front separately, going backwards and forwards, you can't see the pattern on the purl side because the stranded threads obscure it. It helps keep the tension even, and not having to turn the work every row makes tangles less likely. And you don't have to match the sides and sew them together, because the garment will be a tube at least up to the armholes. Traditional fairisle hand knitted jerseys even have a way round this, of making 'steeks,' i.e, knitting the jersey as a tube right up to the shoulders and then cutting the armholes open and picking ups stitches for the sleeves. This is possible with the right sort of Shetland yarn because the fibres stick together and don't unravel, but it's a bit nerve wracking the first time you try it. I always do sleeves on short circular needles as well, saves all that boring and unnecessary sewing up of the sleeve seams. With the right sort of traditional pattern, you can pick up stitches round the body edge of the sleeves and then knit them downwards, circular, gives a really nice seamless finish.
If you choose a pattern with a yoke, the body is usually knitted as a tube up to where the sleeves join in, and then you knit the sleeves up to the armholes, and then you join the sleeves to the body and knit round and round top over the shoulders to the neck, decreasing as you go. This is the part where the fair isle pattern usually come, and it's very satisfying to do.