Swim thought they would put up this advice on injecting as swim has read a few posts where lab rats have had problems, so hear goes.
1

Make sure you have a decent tournique, as this will be needed to help one find a vein
2

A couple of swabs. One to clean the area before injection and one to clean the area after injection, this will reduce the risk of infection.
3

A clean spoon, some citric or vitamin C will do and something to use for a filter.
4

Make sure the needle is in as far as it will go, this will hopefully avoid it coming out of the vein when the tournique is loosend
5

Make sure the blood drawn into the syringe is dark red, if it is light in colour you will have hit the vein and this is not a good place to try and inject so withdraw and try again.
6

Once you have got the dark blood push the plunger in slowly, if you rush this there is a good chance that the vein may blow or you will loose the hit. Every 30 or so mls draw the plunger back again just to make sure that you are still on target, repeat this process until all the liquid has gone.
Hopefully this will help someone avoid getting a ' dirty hit ' .