Auction strategies?

How do you decide what to bid at a mail auction (not eBay)? Especially if
you bid on groups of atamps - album pages from various countries for
example - rather than specific items or sets. What about a mish-mash of
stuff in cartons?

Let's say the lot has an estimated value of $100 - 125. What would you bid?
Why? Does the contents have an effect? Let's say US vs. Europe. Or maybe
better yet US vs. South America. Covers? SSs? What about catalogs and
literature?

Have you ever had a bid accepted for less than you bid? Most auction
catalogs say one raise over the next highest bid but I always end up paying
what I bid.

Thanks for your input. I think all mail bidders might profit from a good
discussion here.

Favorite auction houses?

Any web sites devoted to this subject?

TIA


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