Josh -
Make a packing list of what you think you will need for each trip.
Pack said equipment and check it off the list as you pack it.
When you get home remove all things from the list that you did not use or realize you just don't need.
As you gain expereince you will find that you really do not need much for the average weekend out.
Forgetting a basic like a sleeping pad is just bad form, sometimes it happens but two times in a year seems just forgetful/neglectful.
The list idea helps you think through the process and it really will help pair down the unnecessary crap that alot of people take with them.
The less extraneous stuff you have = the lighter your load = the easier your load is to handle = the more yo can get done = MORE FUN and LESS SUFFERING.
another approach to packing - store all your climbing shit were you can see it, like on a peg board, wire shelves, etc - before you leave look at all the shit you're leaving behind and ask yerself, "hey, did i actually want that sleeping pad?"
i usually feel nervous when setting off for a trip that i might have forgotten shit, so i also as i sit down in the car try to imagine myself doing all of the things i'll be doing on the trip - eating, shitting, camping, cooking, climbing, getting drunk, etc. - and then mentally confirming i threw in the required gear for each of those activities