I have purchased from apmex many times. If you are just starting buy the cheapest, in other words get the most for your money. The pretty coins are of course very appealing but I always advise getting the most metal for your money.
For silver I would go for 90% US coins or 1 ounce generic rounds. If you want something a little prettier go for silver american eagles or canadian maple leaf.
If you are looking for gold, typically krugerands are the cheapest premium (mark up over spot) gold coins to be had (and the most recognized).
Shipping needs to be taken into consideration also. There is flat rate shipping (I believe 9.95 for any order up to $499) so if possible take advantage of that and order as much as you can up to that amount to take the most advantage of the shipping you are going to pay. If you are going to pay with a credit or debit card they are going to hit you with 3% of your ordered added to shipping charges.
If you have a decent local dealer that is the best option. If you purchase regularly and they get to know you a local dealer can be a great asset. However you need to watch they premium over spot they charge and what they pay if you want to sell your metals back.