IMHO, two qualities a domainer needs to learn if they dont already have them are to be patient and to be realistic.
Many names I have sold I had for many months or even several years before a buyer came along - if you are confident in the quality of your names, be patient if you have them listed on Sedo - you are competing for a buyer's attention with millions of other names.
Also be realistic - you will not sell all of your names (you would be superhuman if you did!). I dont know how anyone else does but I sell around 5% of my portfolio each year.
Also times have changed where you could just list your names with various brokers / sites and sit back passively to wait for a sale. Now you have to be much more proactive and actively go looking for those end users yourself.
I have over 1000 names listed at Sedo and I sell probably up to ten every year at Sedo - for me it is simply an extra potential passive source of buyers but certainly not the first means for actively marketing names.
Hope this helps.