The title says it all.

Depends what you are searching for.

If you are using LW 5 or WireShare & open the Advanced Tools from the Tools menu bar option, you will be able to see incoming searches. You can get an idea of what are the popular search terms this way.

There are some clues about searching for things discussed around the forum. Such as being too specific in your search terms will bring in less search results. Some files might not be named as you might expect. That's a user population issue. So varying your search terms might help considerably. The network is quite dynamic. Hosts leaving and new ones starting their session. Likewise the ultrapeers you are connected to will change over time. So different times of the day might bring in a variation of search results. Even an hour or two (or less) can make a difference.

Looking in the search terms, all I see is a few searches for what appears to be CP (you know what I mean,) mixed with a bunch of others. It goes too fast for the search list to be a viable option.
Specifically, things like "kiddy", "underage", etc. WTF IS WRONG WITH PEOPLE!?

Yeah I know, there are some bad types out there. You can use the adult filter via settings. If you're using LimeWire, the original adult filter was somewhat lacking to say the least. Though that might not filter out incoming searches, I'm not sure.

In the Advanced Tools, you can click inside that incoming search panel & control-A, control-C and paste into a text document. But again, porn is super popular on the network and you might find a heck of a lot of such searches.

Are you searching for video, audio or image files? Any specific topics?
This is probably a better starting point.

I like many people on the gnutella network, was on a hunt for audio, mainly old music from the previous century.

Mainly looking for mid-century music.
Additionally, I don't seem to get too many search results when looking up certain topics. (i.e. looking up "Pennsylvania 6-5000" provides only 2 results, when I would expect more)
I use LimeWire Pirate Edition, installed following this tutorial

My replies keep disappearing, so... can't quite answer.

Sorry, Forum censor was having a field day with some of the topics we were discussing. I must have been half-asleep to not realise I was reading moderated posts.

Keep in mind the network is reliant upon what people share. So if nobody is sharing a particular topic then obviously you won't find it. As previously mentioned, sometimes it is worth trying certain unsuccessful searches at varying points of the day (if possible.)

Music:

Try different searches in this order:
artist, album title (unless it's brief), portion of song title (unless it's brief.)

I originally preferred doing an All Types search & then simply filtered it by audio. Else of course you can use the Audio type search. One issue is a percentage of files shared do not have ID3 tags to help with searches, only the file-name gives the clue which is why an All Types search can sometimes bring in a few extra results.

If the artist is a band, sometimes it can be worth doing a gnutella search for the name of the most popular member of the band.