"without losing the money in it".
The money you spent to buy that object is gone. The technical term is that it is a sunk cost. No matter what you do, that money has been spent and there is no way to "unspend" it. The proper way to deal with a sunk cost is to discard it entirely from your reasoning process.
An object is worth what someone is willing to pay for it, regardless of how much it initially cost. You should unload objects in the forum where people will pay the most for it (or where your profit margins are largest).
CL is a good option for stuff that doesn't make sense to ship. Ebay is good for smaller things; the market is much larger than CL. Amazon isn't a bad place for certain things either. Both Ebay and Amazon will take their commission.
Some things make more sense to sell in lots vs selling individually and vice versa, like on Ebay if you have lots of clothes in low end brands, it could make sense to group clothes by size and/or brand and sell it as a lot, rather than one at a time.
Garage sales probably aren't a way to maximize profit but might still be worth it if you value your time. Everything left over at the end goes to charity, for instance. Then you're only out a day or two on the whole deal, rather than dealing with CL for weeks on end.