If you are new to nails then 'more is better than less' at this stage until you learn the techniques of application and it all becomes second nature.
By 'more is better than less', I mean make sure you have an adequate amount of adhesive in the well of the tip and, really for the best bond, you should also apply a small amount of adhesive to the free edge of the nail as well. Tips last so much longer for the client with no 'curling' if you apply the adhesive to both surfaces before sticking them together (just like anything else you glue together).
then simply place the well of the tip against the free edge of the nail at a 45º angle and then lower the well slowly onto the surface ... When you see the excess adhesive squeeze out at the top then stop and apply firm pressure until adhered.