Apply normal eye make-up i.e shadow, liner mascara first.
I would recommend buying some Duo adhesive available at MAC cosmetics and specialist make up shop Charles Fox, Covent Garden. I find the glue in a lot of the lash kits not strong enough to keep the lashes on properly and they start to lift off. This glue however, I have used for years on many clients and never have a problem. It is a very gentle glue as well and suitable for sensitive skin.
Always hold the strip lash roughly in place of where you are going to position it before applying glue as they are more often than not too long and may need the edge simply trimmed off with a small pair of nail scissors so it fits perfectly. Apply glue to the lash strip I usually use the end of a narrow make up brush which can easily be wiped clean afterwards. Allow the glue to become a little tacky for a few seconds before application this will ensure it sticks well.
Apply the lash looking down slightly but directly into a large mirror, magnifying if possible.You can use tweezers to hold the lash in the middle as you position it as close to the lash line as possible and then gently move it to set in line with your own lashes. Sometimes on myself I find it easier without tweezers just using my fingers so play around and find what works best for you. Again at this point I will use a clean make up brush with a fine end to gently press down the lash strip to ensure the glue sets well. You can use cotton buds but I sometimes find fine fibres from them and these can get into the eye.
Repeat on the other eye. Now apply a little mascara if you feel it necessary to blend some of your own lashes into the false ones. From experience this is usually more noticeable towards the outer corner of the eye. The important bit is to get right in at the root of the lashes to lift the mascara though your lashes and into the false ones. To finish off at this point I usually add a little more eyeliner gently to the top lash line this will help to further disguise any gaps between your own lashes and the falsies.