I would echo the sentiments of those who have commented earlier. I personally love this set, both for the uniqueness and the challenge. What other set can make you shrug in indifference at Walter Johnson but get giddy with excitement about Grover Hartley? Patience is definitely a must if you are planning on completion (in any grade). There are a good 75-80 tough cards in the set and several that you almost never see for sale individually.
All of the resources mentioned above are an excellent starting point. My recommendation is to get a good foundation of knowledge of what cards are the most difficult and NEVER pass up an opportunity to add one of those to your collection if you find one for a reasonable price. The super tough ones will always cost you but it seems that there are far fewer collectors of this set than most of the other mainstream sets of the era so that can mean less competition if you know what you're looking for
