sorry to those who don't have kids... you may want to skip this.
i know a lot of people with children elisha's age are at least thinking seriously about (aka: dreading) potty training... and probably those w/ younger littles, too. i think most parents dread potty training almost from the moment they birth their babies. it can be exhausting, frustrating, and messy... but it is also very exciting too! goodness knows, we have been changing wet undies here and there for quite a while so, while the weather is warm (the BEST time to start) here are some of the things we have learned (with the disclaimer that i realize there are many different child/parent teams, and different things will work best for different people-- and some people are amazingly blessed to have children wake up one day asking for undies and never have an accident....but don't count on it!)
i think it is best to approach the whole thing like we do walking, eating, and all the other things our children gradually learn to do on their own--- meaning: it is a process. you don't have a marathon weekend where your child starts out immobile on their backs and ends up walking. their are many steps in between that take a lot of development to master, not to mention help (remember holding their hands for so long as they learn to walk independently?) training our children to ignore the feeling of eliminating and being wet/dirty for years and then all of a sudden expecting them to recognize the feeling of needing to "go" and doing it in a new place, a new way, is a LOT to ask... and can be very frustrating for both of you. my approach (and i don't claim that it is convenient) is to try to at least keep a little awareness along the way- cloth diapers and changing frequently has helped, but also keeping a little potty around and letting my babies (anna as soon as she could sit supported) sit on them from time to time. i try to do it at a consistent time, like right before and/or after naps/bedtime... and most importantly-- when i KNOW she needs to go... you know what i mean. if your baby is around you, you usually know when she is starting to poop. why on earth do you want to sit there and watch her get used to doing it in a way and place that you will desperately be trying to tell her not to a few months/years later. do yourself(and your child) a favor and time the time to grab her, say "hold on a minute, let's poop in the potty instead", and then rejoice in not having poop smeared all over her little bum. wiping a potty with clorox wipes is a lot easier that getting poop out of all the crevices of a squirming child. even if you don't "catch" every poop, at least they will be familiar with the idea and the feeling of pooping as they sit on the potty.
having a little naked bottom outside time while the weather is nice can be really helpful to let your child/baby become aware of the feelings of eliminating. talk to him about what is going on (try to act nonchalant if they poop in the grass ;-)... remember- easier to scoop off of the grass than clean poopy undies later ;-)... notice their "cues"-- sometimes your child may do a little dance or get antsy, or just pause and look off in the distance before or during eliminating--- notice this, it will help when you get to the next step of undies inside and getting them to the potty in time. and again, talk to them about everything. help them learn how it all works, point out what they are doing. if you don't like the idea of baring all for the backyard to see, get some cotton undies and watch for wetness streaming down their legs (they don't take much space in the wash) or just put them in a long shirt.
the official recommendation from pediatricians is to put children on little potties because they will feel more secure with their feet on the ground. we really like the "baby bijorn little potty" it is only about $10... i like potties to be all one piece-- they are easier to keep clean. ikea sells a simple one piece potty for $3. it is a cheaper option (maybe to keep in the basement, outside, or in the car)... but it is a tiny bit higher than the bjorn, so not as good for little bitties... and it tips over a little easier and the bowl shape causes a little more sloshing when carrying to the potty. if you want to high end potty for $20 you can get the "babywunder deluxe" clear potty... again nice one piece, but clear, as the name implies. sounds weird or gross at first, but is great because you don't have disturb the child to see if there has been success, and you can communicate with them as they go, b/c you will sure of what is happening in there ;-) it is shaped like the bjorn , so it is shorter and more stable.
now, a word about pull-ups: i cannot tell you how many times elisha has explained to me that "pull-up: it it it like a diaper" i try to tell him to pretend they are undies and to keep them dry-- but you can't fool the little guys! they are good on occasion ( a stomach virus! or long car trips, or times of absolute need for dry clothes, but you will still be able to take them to the potty) ... but in general you are just using more expensive diapers.
my last tip for the day is: don't ask your child if they need to potty-- just say " its potty time, let's go give it a good try on the potty." what do toddlers love to say? "no"... they are usually not going to choose to stop what they are doing to go potty, just get them used to taking potty breaks. another thing we have learned is that sometimes needing to potty makes kids fussy... so they may resist using the potty most when they need to go the most... strange, i know. but that is another good reason to give babies a chance to pee or poop before bedtimes... a lot of times they will go to sleep easier if they have an empty bladder and a dry diaper.
if you have read all of this, you will find it very helpful and well worth the effort!