Many people don't bid on items until the last minute so if you are checking prices its best to put things into watched items & see what the final sale price comes out to.
Free listings weekends come up quite regularly so it won't hurt to have a look now to get an idea of realistic end of auction prices & think about either setting a reasonable starting price or biting the bullet & pay to advertise them on buy it now, remember you don't pay a fee unless it sells.
One thing bearing in mind is that Royal Mail have changed their rates recently so its a good idea to weigh any items you are selling before you create your listing so you dont get any nasty surprises when you post them, I use parcel2go for my larger or heavier items they give a good range of price options & many of them include collection so you dont even have to worry about getting them to a collection office.
Also offering personal collection can give you the edge against other sellers, I often look for large or heavy items close to home as you can save quite a lot if you don't have to pay postage & always offer collection on large or heavy items for sale.