How to Spot a Faker
There are a lot of fakes out there in all worlds, including the intangible ones. When you reach out to a well-known entity there's a strong chance you will attract fakes. The bigger and more popular the name, the higher the risk of fakes. How do you go about making friends while avoiding fakes?
First, recognize that it's not always a fake!
Big names sometimes have messengers and lower-ranked folks who will stop by on their behalf. This is because, even though they are powerful, they are seldom omnipotent and have limited resources and time just like anyone else. If it looks like the one you were trying to contact but feels "off" try asking straight up if they are a messenger.
If they answer "Yes" ask them to send a message to the friend you want to contact. Next time you try to contact your friend ask about that message you sent. If your friend doesn't know what you're talking about then whoever was visiting you was not a messenger. Discard whatever they told you!
If your friend knows about the message, you found a messenger. Get used to the messenger's presence and mark them like you would one of your friends so you can know it's them. Messengers can be good friends, too. As a bonus they know who you are trying to contact and they can give more perspective on them from a new point of view.
If they answer "no" move on to the other methods below for authentication.
There are several simple ways to double-check someone is who they say: Questioning, Signature, Energy Print, and Password. Personally I would advise against the first two when you're new and here is why...
Method 1: Ask them questions
This is a popular method. Simply ask the entity questions about themselves and see what they answer! The problem with this method is that unless you have a long history with someone you likely don't know them well. This can lead to misunderstandings very easily. Myths can be wrong/outdated, which doesn't help things. Myths also are well-known which makes it easy for well-versed entities to fake being someone else. As a consequence I do not recommend this method.
Method 2: Get their autograph
Literally have them write their name/sigil/whatever for you. This sounds like a good idea in theory, but if a sigil/signature is so well known you can find it on the internet chances are anyone remotely well-versed can fake it. If it isn't well-known you might not be able to know if it's a forgery unless, again, you already know someone really well! I actually got tricked like this early on so it's more likely than you might think.
Making things even worse is the writing itself. You need to be able to or you need to be able to "see" clearly enough to be able to tell things like differences between two people's handwriting. This is hard enough in the material plane, but next to impossible for most beginners. Alternatively you need to let them move your hand to write for them. This is partial possession and extremely dangerous as you don't know who is doing it. It might even be you drawing/writing subconsciously and not them. You'd end up making the forgery for them.
As it's so easy to fake and hard to verify I don't recommend this authentication method.
Method 3: Get their "thumb print"
All beings have an energy signature, even non-physical ones. This technically can be faked, but the sheer force of will to keep the charade up is intense and not likely to be held for long by a lesser entity. There also will be flaws which will become more apparent the more you get to know an entity. Energy flows, flaws, and features make everyone unique, like the swirls of a thumb print.
When you first contact a new friend ask for them to leave an energy signature for you. Feel free to call it a "thumb print" of energy. Read this print well and get very familiar with it. Stronger entities will leave more lasting prints which gives more time to get familiar with it. When someone shows up claiming to be your friend simply read their energy. If the prints don't match, it's a fake!
This method require more focus, but is nearly foolproof. As you get stronger checking for energy patterns will become second nature making this one very easy to keep up and use. I do recommend learning it!
Method 4-A: Password Please!
This works best once you have established a relationship with someone or you are 100% sure you are talking with the real deal. Same for the Knock method. Basically set up a pass phrase with that friend. Perhaps it's a fact only you two know, like something you did together. Or maybe make up a short poem and each of you recites half of it, them first. Change it up every few meetings to prevent others from guessing it.
Either way you must NEVER give their half away! Don't think about it when asking for it, just listen for it. Thinking about it can lead to the risk of you accidentally leaking it which kind of nullifies the point. On the up side, this works great if you can "hear" well but are weak on energy reading.
Method 4-B: Knock to Enter
This can take two forms, depending on what you're good at: an energy barrier or a semi-physical action. I lump this in with the password as it's a form of physical password and best used when you are 100% sure you know who you are dealing with at the time you set it up.
Barrier Version: If you don't want ANYONE else to work with you set up an energy barrier backed up with protective barriers. Leave only one way in and out of this energy barrier. Either have a lock and key sort of setup or make it very difficult for an entity to traverse unless they know the way... like a maze only for non-physical space. This will keep out anyone on the weak side, especially those who don't want to deal with your barrier. Give the key/path to your friend so they can come visit. You won't need to redo the key unless someone breaks your barrier or the barrier is taken down.
Knock Version: Have a specific physical reaction that lets you know they are there. It could be a literal knock on your energy in a specific pattern, like knocking on a door. Or perhaps they could touch you in a specific way that lets you know it's them. This is less secure but allows anyone to come visit while giving a means of subtle verification.
Both knock versions are based on your own skill levels. If you suck at barriers, the barrier won't be very helpful until you become good at barriers. If you can't feel when you are being touched the literal knock won't be useful. There also is the low risk an onlooker might learn your knock and try to use it. I would suggest backing either of these up with the thumbprint method, just to be absolutely safe.
What if they don't want to give a means of identification?
You can bet this one is a trickster at the least if not an outright fake. Never trust an entity that refuses to identify themselves in some way, especially if they claim to be someone well known. Well known and strong entities have nothing to fear in letting you know who they are, especially if you two plan on working together.
What if they won't/can't give a name and an energy print? Even weaker entities should be able to give you at least a name to call them and leave some sort of energy print for you to follow. A total lack of energy print may mean they're imaginary. Clear your mind and try again later. A lack of name can happen in some weaker spirits. Try giving them a nickname. If they refuse a nickname entirely, worry: it means they are up to no good and don't want to be identified. Use a cleansing ritual to dispel them immediately!