First thing's first, getting the best deals to your destination. You'll want to sign up for travel updates at sites like www.travelzoo.com, www.shermanstravel.com, and www.octopustravel.com. These sites send email updates with weekly or monthly deals that I've often taken advantage of.
As far as searching for flights goes, the cheapest flights I've found have been using www.kayak.com for general travelling. Specific airlines for South and Central America (check these before checking general search sites) are TAM airlines, GOL, BROL, and TACA airlines. In the lowland tropics, the USA winter (Dec-Apr) is the dry season (when it's very hot) and the USA summer (May-Nov) is the wet season. It may be cheaper to visit the tropics during the wet season, as there is more rain and humidity, and less tourists. When I went to Costa Rica in June, I had the whole of Manuel Antonio (one of the greatest vacation spots on the Pacific side) to myself.
WHAT TO BRING
If you are visiting the tropics for the first time, here is an important list of essentials:
SUNBLOCK, SUNBLOCK, and more SUNBLOCK,
as you're close to the equator and the
sun burns very hotly (is that a word? :P)
Bring rainboots. These are the
best thing to walk through the jungle in.
They not only look really cool, especially
with some cute shorty shorts, but protect
you from snake bites (yes, the most deadly
of snakes live in the tropics, but don't let
that scare you off. In my years of experience
in the jungle, I haven't had any trouble) and
from the muddy wet ground or small streams
or ponds you may run into while exploring.
They are lighter than hiking boots but work
just as well. The only problem with them is
they do get rather hot. Wear light socks.
Well worth it in the end, though.
The jungle, being covered by a massive
canopy of tall beautiful trees, gets
rather dark at night. Pitch black, in
fact. So you will definitely need a light
in case you get stuck in the dark or fancy
a bit of night-meandering. This is when
the jaguars are active, after all. Lol,
kidding, but the caimen are, if you
happen to find yourself around bodies
of water. In any case, a headlamp is
useful because it lights your way while
still allowing you the use of both your
hands, which comes in HANDy (get it?) if
it's slippery or steep.
Essential for life. In the least, bring
an empty bottle that you can gather all
your sweat up in and drink that.
Great to tie your hair back (yes it's HOT
out there) or wipe your face, swat bugs,
tie wounds, or collect various kinds of
feces from exotic rainforest animals that
you're facscinated with.
Two words: Bug. Spray.
Yes, very necessary. Not only are the mosquitoes,
blackflies, sandflies, and sweat bees extremely
annoying, they can carry diseases such as dengue
fever, yellow fever, malaria, and more. And you
don't wanna get those things, trust me.
This is my personal one, as it's not a necessity,
but did come in handy for me when I got TICK BOMBED
in Belize. SO not cool. I was innocently walking
through the jungle, thinking on the GOOD OF THE
SPECIES when I walked through a tick-egg-sac, which
proceeded to explode all over my leg (luckily I
was wearing long pants). Now there were over a
hundred teeny tiny ticks in the egg sac, and my
leg was quickly covered. I needed to get them off
before they crawled under my pants and dug in for
a feast. My supervisor (for a research project we
were working on) just happened to be carrying a roll
of duct tape, and tore off a large piece and began
pulling off the ticks with it (apparently the only
real way you can get them off your clothes, as you
can't just flick them off cuz they are sticky bastards).
So take this advice as you will, but I'm sure glad we had
the duct tape.
For all the wildlife you'll spot! The only time I
didn't bring my camera into the forest is (of course)
the time I spotted a cute little mouse oppossum in a
tree and it let me bend the tree down and pet it. So
just goes to show...*shrug*
Also great for snapping quick shots of the offending
monkeys who throw sticks and pee at you so you can
report them later.