You’ll make this decision based on logistics and your personal preferences (or the preferences of your group).
You’ll need to take into account how many people will be involved in the spell casting. If it’s just you, make sure you’re spell casting in an area that you feel 100% safe in. You’ll likely be preoccupied with your magic, and you won’t want to be constantly looking over your shoulder for any unsavory people. If you’re on public property like a park or preserve, check the local laws. Some places have restrictions on having a fire during certain times of the year. This may mean you can’t use your candle or incense tools in these areas.
If you’re practicing with a group outside, make sure that it’s ok for you to gather there. You don’t want to get any unwanted attention for disturbing the peace, even though personally, I’d love to look out my window and see a group of witches doing some badass magic!
Another option is if anyone has a large yard you can use. You can also check online or locally for any nice pavilion or outdoor spaced you can rent hourly or daily.
Often times, this ends up being the simplest option for many solo witches. All you need is a place big enough for you. The downside of this you might get interrupted by well-meaning roommates or family members. To avoid this, you can communicate with people ahead of time when and how long you need to be left alone for your spellcasting. Another option is to spellcast when no one is home.
If this just isn’t going to happen in your house because of your hyper dog, your enthusiastic significant other, or your nosy neighbor is sure to disturb you during your magic, check out peerspace or Airbnb. There are also small meeting rooms you can reserve in public libraries and community centers for free or low-cost.
Again, you’ll have to follow the rules so this may limit what kind of magical tools you use, but if uninterrupted privacy is a concern for you, this could be your best option.
If you’re working with a group, you’ll have to work around the obvious constraints. If you’re using incense or oils, make sure that no one has an allergy, is pregnant, or has other health concerns that may be compromised by the use of certain magical tools. Always practice fire safety. Never light incense around children or pets, and always make sure the room is properly ventilated.
The most important thing to keep in mind when choosing a location is to make sure it feels good. You know when you walk into a coffee shop and you turn around and leave immediately because the energy just feels funky to you? That’s your intuition speaking to you. Honor those nudges. It will make a big difference in your spellcasting experience.