Leeches like the ones Hook supplied a link to above are great. They are about all I use now as far as leeches go. I usually use smaller gold beads though, and you can tie them in a variety of colors, (Black/red, green, maroon, brown, etc).
I also carry a few wooley buggers, and they always work well in the colors mentioned above, as well as the pumpkinhead variety.
Small damsel nymphs in yellow and or green are great flies, along with their big brothers the Dragonfly nymphs. Gomphus patterns are great Dragonfly impersonators and fun to fish, but there are lots of dragonfly nymph patterns out there, so start with ones that are simple to tie.
As far as chironomids go, I'd start by making chromies and black sallys, in sizes 10, 12, 14, and 16. Those 2 patterns will definitely get you off to the races. A lot of days I start with these patterns and never end up switching. The fish will usually hit 1 or the other, or both.....
You will probably want a selection of dry flies as well, as they are the most fun to fish. Tom thumbs and Mikaluk sedges are a good place to start with dries, and you will probably want a few mayfly patterns in there as well.
A simple scud pattern like a shellback scud in a few colors is good to have as well. I don't fish them a lot, but they have been day savers before.
Also the old doc sprately will usually get you a few fish, red ones can be especially hot.
Halfbacks and fullbacks in different sizes are another few you'll probably want to carry, and are simple to tie.
One unnamed pattern I never leave home without, is tied on a streamer hook, sz 6-12, but usually on an 8. It has a short tail made of pheasant tail fibres, a medium, olive green chenille body, and a few wraps of short hackle around the head of the fly. This fly is tied with red thread, and is much more successful if you finish the fly with a prominent red head.
As far as patterns used for the local lakes, most of the flies mentione above will work, but one I've had particular success with is just a #10, 12, or 14 scud hook, with a dark colored superfloss body, a gold wire rib, and some short sparse hackle at the front. I fish it on a floating line and vary the retrieve until I find what works.
There are going to be more patterns to add to these of course, these are just a few standbys off the top of my head. You will also want to add a sinking line to your arsenal, for starters either a type 3 or 4 sinker or a clear camo intermediate line will work great.
Have fun and best of luck!