As the plant grows up the cane, remove any of the lower side shoots that start to form but do not remove the large leaves growing from the main stem as these leaves carry food for the axial tip as it grows upwards. Carry on doing this until the plant reaches the required height, but do not remove the last three or four side shoots from the top, these will form the head.
Pinch out the growing tip of the main stem and allow the side shoots at the top to develop and pinch out after three leaf nodes as you would when growing a bush.
Leave the large leaves on the main stem until they drop naturally or until you have a reasonable sized head on the standard. Once the head has started to form has good leaf they can be removed but I like to leave them as long as possible, these are the life support system of the plant and it helps thicken the stem.
A Full Standard
Multi Twisted Stem
Trim back the head of your standard to about three leaf nodes in the first year to help with a good shape for the following year & make storing easier.
Standard fuchsias can be over-wintered in a frost free environment: a garage, shed or greenhouse. Ideally a minimum temperature of 5°C is necessary.
Many hardy fuchsias make good standards, but although it's classed as a hardy variety still means top growth will be killed off if it gets too cold which you don't want in a standard, so treat a standard as half hardy in any event. Lag the stem with pipe lagging to protect the stem against the winter weather and don't over water.
In the spring re-pot with fresh compost as you would with your other plants, but maybe an inch deeper to help develop more root for stability. Once new growth begins it needs as much light as possible, yet kept frost free until the threat of frost is past. Ideally in a frost free greenhouse or conservatory, but if you don't have this then putting the plant out on milder days and bringing inside in the evenings will be successful.
When you see evidence of new growth, increase watering and spray with tepid water to encourage new growth, and grow on as you would a normal bush. As the head develops pinch out the growing tips and cease this in May for a flowering plant in July. There will always be side shoots developing from the stem below the head, which should be removed regularly to maintain the shape.