I'd warn against circle lenses. A lot of people use them with no problem, but they are a hazard that just isn't worth it. Most cosmetic lenses are not approved by the FDA and without a valid prescription, they are actually illegal to sell in the United States. These kinds of lenses could potentially cause infections, ulcers, perforations on the cornea, and even blindness. By the time you feel any pain or discomfort, the damage has probably already been done and could possibly be irreparable. Cosmetic lenses should definitely be used at ones own discretion. Be sure to know the facts and don't let anyone else's positive experience sway you.
I agree, however, with the white eyeliner on your waterline. It gives the illusion of larger eyes and then you can line underneath the waterline and apply a few individual false lashes for a real pop.
Have you ever tried circle lenses? Those make your eyes WAY BIGGER!!! You can get them in a natural color or wild ones. I have a pair of light green ones that are a little bigger than my iris and it makes a big difference.
You can get them on prettyandcute, keautystore, amazon, and ebay.
I too have brown/hazel eyes that I LOVE! I take a black, creamy, pencil liner and I tightline my top lash line. Then, I also tightline the bottom lash line (just the outer fourth though). Then, I put on my mascara! This makes my eyes noticeably bigger! Also, I sometimes wear a white or pale brown shadow. Hope you find something!!
Use eyeliner on the top corner of your eye 1/4th and then the bottom corner 1/5, flicking upwards, just slightly. This creates a nice big doe shape! Then, put a white, shimmery highlight on the inner corner. This will make your eyes look huge!
Also, curl your lashes upwards. Falsies make eyes look HUGE. Don't line your bottom lash line, it makes eyes look smaller.
Use an eyelash curler before putting on mascara. Believe me -It works! But the drugstore or dollar store brands are just as good as the $20 ones at Sephora, IMHO. Do two sweeps of mascara over eyes. Black is going to be the best shade for mascara and eyeliner because it is the most dramatic and stands out best. If, however, you are very very pale in face, eyes, and hair, and feel that you cannot pull off black, then try a charcoal grey or dark brown.
Eyeliner is also what makes eyes P-O-P! Line both top and bottoms lines, but if you want your eyes to look bigger, do NOT line the waterline. Lining the waterline makes eyes shrink, eyen if you are also lining the bottom line it would help the cause to trying to make them look even bigger. However, after lining both the top and bottom lashes, you could get a Nude color liner (or even white) to line the waterline. This natural color against the black contrasts and adds extra pop for the eyes.
For eyeshadows, remember to use three colors - a highlighter (usually a white or natural color for the top over the lid), a base (that will go on all over your lid), and a contour that will be used in the crease. Check out Smashbox - they have eyeshadow trios that are great, I particularly love the white/silver/black shadow trio when I'm doing a smokey eye look! http://www.sephora.com/product/productDetail.jsp?k