1) Choose the right foam for the flowers you are using. Generally, green water-retaining foam is for fresh flowers and foliage, whilst the brown stiffer foam is for dried or artificial flowers.
2) Think about the size of the space in which your arrangement will be placed, and choose the size of your container and flowers accordingly. A huge vase and lots of flowers will look overcrowded on a small side table, and equally, a small vase and a few flowers would be completely lost in a large area such as a Church.
3) When making an arrangement for a dining table, keep it low (no more than 9" high at its highest point) so that guests can converse with each other across the table without having to fight their way through the flowers!! However, if you are making an arrangement for a buffet table, always make the arrangement on a pedestal or in a tall vase to bring the flowers up and out of the way of the food.
4) Use flowers in different stages of development, from bud to full bloom. Place the buds at the top and edges of the arrangement, and the largest fullest flowers in the centre of the arrangement, more towards the bottom of the design, to form the focal area. Half-open flowers can fall anywhere between these two.
5) Use flowers and foliage with different shapes, colours and textures, for a more interesting design. Generally, you need three sorts of shapes - line material (straight leaves, such as Iris leaves, Bear Grass, Phormium, and flowers such as Liatris, Foxtail Lilies, etc), generally used to form the outline shape of your design; rounded materials (such as Carnations, open Roses, Gerberas, etc.), generally used as the focal flowers; and intermediate or filler materials, (such as Gypsophila, Waxflower, small, ferny foliage) to act as stepping stones between the other materials, and to "fill in". Use different textured materials such as ferny, furry, bold, etc., which will reflect the light differently and give interest to the design. Try to incorporate different coloured foliage, according to your colour scheme, which again will add interest to the design.
6) When using open flowers such as Roses, Daffodils, Gerbera, etc., try to turn some of them at different angles to show a different shape. Never arrange all your flowers facing forwards - this is very boring!!
7) Always remove the stamens on Lilies. There are several reasons for this: a) the pollen will stain the flower; b) The pollen will stain any clothing or furnishings it may come into contact with; c) removing the stamens makes the flowers last a bit longer (this is because a flower which has been pollinated has completed its job in life, and therefore dies fairly soon after pollination - by removing the stamens, this is prevented, thus making the flower last longer). NEVER cut off the stamens with scissors. This is ugly, and unprofessional, and causes discolouration. Use your fingers to pull the stamens off, leaving a nice neat point which will not discolour.
8) Make sure that your colours are evenly balanced - this means not having more strong colours over one side of the arrangement than the other.
9) Always allow some space between the flowers to prevent a crowded effect. Constance Spry always said one should leave room for the butterflies!
10) Fillers such as sand, small stones or gravel can be used under the foam to raise it up so that you don't have to use so much in a deep container. This will also add weight to the container to make it more stable.
11) When using clear containers, add marbles, layers of interesting pebbles, or shells to hide the foam.
12) Position a container with three legs to show one leg directly in front. This will help the balance of the design, and prevent it from falling forward with the weight of the flowers.
13) Always check that baskets with waterproof linings do not leak before using them. Minute punctures in the plastic lining do not always show up, and can result in unexpected leaks. Fill the basket with water and leave for around half an hour, somewhere waterproof like a draining board or sink. By this time, any minute puncture in the lining will be leaking water, and you will know that the basket leaks. If in doubt, line the basket again with polythene, clingfilm or tinfoil.
14) Never place containers directly onto polished surfaces. Any unexpected water spillage can cause damage which may be difficult and expensive to rectify. Use a waterproof base under the container.
15) Never place your arrangement on top of electrical appliances. Any stray water or an unexpected leak can cause more damage than you had bargained for!