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Yeah, I have a lot of stuff, but I'm going to make a separate post for it.

Alright. The most common that I know of, fingers (obviously), feathers, toothbrushes, hair brushes, really anything with soft bristles, a pen... pencil
All of which can be applied to the feet
Some tools can be used in other places, and give off a better reaction than the rest. anything soft can be used just about anywhere. As for the brush, if it's not soft don't think aobut it. The pencil, not so much, but the pen, it could be used elsewhere

Anyway to restrain the victim's arms and legs will come in handy. To keep the arms out of the way and to stop them from being able to protect their ticklish spots. A blindfold used for suspense, and to increase the other senses, such as touch, making them more ticklish. A type of lotion, to descrease friction on bare skin so your fingers can slide around easier and tickle more.

Tickling the Feet:

Restraining the feet is your best chance. Keep him/her from kicking his/her feet, and from knocking your hands away. Don't tickle his/her feet too much, or they'll desensitize, and her feet will be less ticklish. Now, on to the actual tickling. All the objects I named way up there will definitely tickle. Cotton balls, Q-tips, stuff like that.
If there is no certain part of his/her feet that is ticklish, start searching. Check the heel, the soles, the arches, the insteps, the toes, inbetween, and under the toes. By pulling his/her toes back, or restraining them and stopping them from moving, you'll stretch the arches and make his/her feet more ticklish. Same with the lotion as well. Even check the toes themselves.

Elsewhere:

tickling slow, or fast, depending upon the area can have a more or less ticklish effect
Being suspensful can apply more ticklishness if used correctly.
I'm running outta stuff =/
I love tickling the ribs. If the ticklee's arms are trapped and restrained away from the body, dig your fingers into his/her ribs, not too hard, and scribble your finger's either up and down, or in a circular motion really fast, or slow, depending on your techniques. If tickling up and down the ribs, drag a finger either up or down, poking the ribs and slightly inbetween.
As said before, some tools work better in some places than others. Take the ribs, for example. using something, such as pen or pencil might not be the best idea, but a feather or Q-tip, something soft, would work better.
Now, the stomach, like the feet, has more than 1 ticklish spot on it
Right in the middle, the sides, the navel, the waistline, and right under the ribs. What I like doing, is taking a pillow, or something thick with comfort, and place it under the ribs so they stand out more.

i like to use a pen and draw on their soles then a toothbrush to clean them off and begin again

I just copied and pasted what I told my friend on YIM

Every person has different more/less sensitive points. This is why I always do (and suggest) a simple technique, when I have a first session whit a lee/ler I meet for the very first time: the mapping.
The 'ler have to stroll his/her fingers veeeeery softly and slowly over the whole body of the 'lee and pay attention to the reaction he/she has in every moment, so to find the most sensitive spots.
Once all spots are found it's time to begin the real session and do some serious tickle twisted

i think fingers/hands work the best

Not much can beat an electric toothbrush inbetween the toes or the bristles of a hairbrussh scratching against the feet.