I had been trying (and failing miserably!) to achieve perfect upper lid eyeliner and flicks for a while so thought it was time I did some research into the best products to achieve this look. The general consensus online seemed to say that MACs fluidline gel liner was the product to go for.
I went to one of London stores and had a chat with one of the make up artists in there about achieving good eyeliner with flicks. She recommended one of their angled eyeliner brushes to apply the liner with and felt that this would be the easiest brush to start with. If you are hoping to achieve a dramatic look, then this product definitely creates that effect. It is quite easy to apply, but does take some practice which is what the make up artist in the shop had also advised. I recommend you put some of the gel onto the back of your hand and apply from there to make sure you don't have too much on the brush. Despite looking small, the pot does last a good amount of time and the product lasts well when applied and doesn't smudge. It dries very quickly once on so you can continue applying your other eye makeup very quickly. It you are looking for a less dramatic, daytime look, the I'd suggest a black kohl pencil liner.