If you want plants to survive and thrive follow this guide.  Before we got our volunteers to follow this guide (as well as planting the right species in the right sites) they were getting a less than a 50% survival rate.  We now get close to a 100% survival rate.  Note that optimal planting methods vary in different parts of the country.

1. Planting is generally best undertaken during autumn and winter, although the exact timing depends on rainfall and how damp the soil is.  Sometimes rainfall can be so regular that planting can be undertaken throughout the year.  At most sites planting can be undertaken throughout the year if plants are going to be watered manually on a regular basis.
2. Ensure the root-mass is moist before removing the plastic bag.  It is best to water plants the night before planting them so they are not too wet at planting time.
3. Make a hole at least 10cm deeper & wider than the root-mass of the plant.  Place the soil in a tidy pile next to the hole so it is easy to recover (usually all this soil will need to be put back around the plant).  Break up hard ground if necessary.  If it is rock hard ensure you have selected the right species for the site.  Return some loose soil to the bottom of the hole.  Moisten the soil if it is dry.
4. Try putting the plant (still in its plastic bag) in the hole to check that when it is in position the top of the root-mass is slightly lower than the lowest part of the surrounding soil surface.  This provides maximum water collection/retention capacity.  Adjust the size of the hole if necessary.
5. Remove weeds from the root-mass.
6. Gently remove the plastic bag from the root-mass.  Gently loosen any matted roots on the outside of the root-mass.  Do not disturb more than 10% of the root-mass as doing so could kill the plant (some plants are more sensitive than others when it comes to disturbing their roots, but this is a good rule of thumb).  Ensuring the root-mass is moist before disturbing it reduces the impact of root disturbance.
7. In dry sites put a few of the water crystals in the bottom of the hole so they will be in immediate contact with the roots.  Dry sites include those that might become dry in summer as water crystals will last for at least a year and see the plant through a dry spell, enabling it to become established enough to handle the next dry summer.  Moisture levels at other times of the year are irrelevant.
8. Return soil to half way up the root-mass, gently pushing it down with your finger tips as you go.  If required, add fertiliser and most of the water crystals at this stage.  In dry sites this encourages roots to grow outwards (rather than downwards) because rain is unlikely to soak far below the soil surface.  Fertiliser should be placed near the sides of the root-mass and be mixed with soil.  This maximises the amount of fertiliser that will soak down into the root-mass and allows the roots to grow into it gradually.  Putting fertiliser hard up against the roots at planting time may burn them. Water crystals should be placed hard up against the root-mass so they are in immediate contact with roots.  In total, a small hand-full of fertiliser and a small hand-full of water crystals should be sufficient for each plant at most sites.  Fertiliser such as sheep pellets should be moistened first.  Water crystals must be at least partly charged with water first.  The use of too many water crystals or uncharged (dry) water crystals can result in the plant being pushed out of the ground as they absorb water and expand (water crystals expand to about 300 times their original size).
9. Fill the rest of the hole with soil and press it down with your hands as you go to ensure there is firm contact between the soil and roots and so it is firm enough to hold the plant in place against wind (bearing in mind that in windy sites plants should also be staked and tied).  If the soil is too loose around the root-mass roots may not be able to absorb water and nutrients adequately and strong wind may push the plant over.  If the soil is too firm water may not be able to soak into it adequately.  Pushing down on the root-mass with your foot may also damage the roots.  Don't put fertiliser or water crystals close to or on the final soil surface or weeds will benefit from them.
10. Make a dam around the plant to enhance water collection capacity, especially in dry sites.  In dry sites water collection can be further enhanced by making small trenches that lead water downhill to the plant (swales).
11. Put a think layer of mulch within at least a 20cm radius of the stem & ensure no soil is visible through it.  This suppresses weeds and greatly enhances water retention.
12. Put a stake beside the plant if it is in a windy site, amongst grass or in a situation where it might otherwise become obscured from sight by vegetation growth (even grass can completely smother and kill seedlings).  Staked plants are easy to find and "release" from competing vegetation growth during their first couple of years, after which they can usually look after themselves.  Put the stake next to the root-mass, not through it, as the amount of root damage caused by the latter would probably kill the plant.  If in a windy site tie the plant to the stake one third of the way up the height of the plant. Tie it in a figure eight fashion with an extra loop around the stake to prevent it slipping down.  Do not loop the tie around the plant's stem as this can cause damage and impede growth.
13. Water the plant in and ensure surrounding soil is moistened.  If the surrounding soil is dry it will draw water away from the root-mass.