A lovely hobby, but where to start if you wish to collect the original My Little Pony's? Good place is right here on e-Bay auctions, car boots, jumble sales, Newspaper adverts etc. Read carefully the Seller's description of the pony or ponies for sale as unless you are experienced at renovating them then a pony with a really bad haircut, badly rubbed symbols or pen marks all over it will always remain just that. Always bear in mind that these were produced by Hasbro as childrens' toys so the majority have been played with over the years and now are eagerly collected by grownups who used to play with them and now want them back.
To my knowledge there are well over 800 different named ponies and that's not including the Dutch, Brazilian, Peruvian Italian, French and Spanish variants so as a beginner decide what to collect first. Right from the start maybe with a set of 6 original earth ponies, Pegasus ponies, Flutter ponies, Babies, Twice as Fancy, Family Friends etc. and build up from there. I started my collection with the very first ones released, Cotton Candy being one of my all time favourites. Condition-wise good idea to buy a pony who has minor faults such as pen mark underneath it's hooves, slight rubbing of it's symbols or eyes, one or two plugs of hair missing from the mane or hair slightly dry perhaps. That way you have the pleasure of a decent looking pony when on display and can always upgrade to a more perfect example when money permits and sell off your doubles.
The vinyl material used for the bodies absorbs felt tip pen marks and is not easy to remove. My top tip for displaying ponies is always away from bright sunlight as you would be surprised how sunlight can fade a pony's vinyl body, hair and painted symbols. Personally I always gently wash the body in warm soapy water, trying not to get the pony overly wet as water left inside the body will create rust to the metal ring inside holding the tail in place discolouring the tail hair and even the vinyl in some cases, plus of course, it encourages mould to grow inside the pony. After gently removing the surface dirt and marks I progress to the hair using a running tap of luke warm water and holding the pony downwards so trying to stop as much water as possible entering it's body. I use Johnson's Baby Shampoo as it's lovely and mild, mane first and then the tail, rinse thoroughly and then apply generous amounts of Pantene Pro-Vit. Conditioner, work throughout the hair thoroughly, with bad cases of frizzy, dry hair comb it through and leave for 2-3 minutes then gently, but thoroughly rinse out every last bit. Always use luke warm water as you don't want to ruin the nylon hair. Pat excess water out with a towel, comb the mane and tail so it's tangle-free and I always leave my ponies tail hole facing downwards on top of a warm radiator to thoroughly dry out the inside of their bodies. Hopefully your pony will once more look like new! Once you become used to the construction of the ponies you can undertake minor renovations like replacing a couple of missing hair plugs in the mane or replacing a lost tail which of course involves removing the head and re-gluing when finished. Although if you do and then decide to sell them on e-Bay you must state in the description that this work has been carried out in fairness to your potential Buyers. A lot of folk buy old ponies to create whole new characters by customizing them in creative ways and they really do take on a new lease of life. Great fun and often saves the life of a badly damaged pony who otherwise might have ended up in the Knackers Yard!