I collect spiders in my field sites primarily with pitfall traps.
|Soapy water breaks the surface tension, drowning anything that falls in :(|
Next, the spiders need to be sorted out from the rest of the gunk. To reduce the amount of such debris, I recommend using some sort of trap cover while it's in the field.
|Spiders, ants, beetles, etc. set aside on the left.|
|Camera pic, apologies for the blur.|
Finally, I can actually identify the specimens. It takes time and repeated efforts to learn how to identify a spider to even just family, but I'm now pretty quick at identifying to genus. In the future, I may write a post about how to identify spiders, but for now here are some good links: