Go through the promotion's Terms and Conditions and wagering requirements to determine what you need to take into account when claiming a Free Spins bonus.
Free-spin bonuses that don’t require a minimum deposit usually have low wagering requirements or none at all, but the number of spins you get will generally be lower. This makes using your no-deposit free spins simple, as you won’t have to sit through hundreds of spins in one go.
If you have to stop playing and will return later, you can pick up right where you left off; however, don’t forget that free spins can expire. Check the Terms and Conditions and look for “bonus valid” in the phrasing, which will specify how long your free spins can sit around for.