Most of the following information is available here and there in various posts on different forums, but I thought I would consolidate the information for the sake of convenience, as well as adding my own experience to the mix.
There is no drug out there that is completely safe. However, there are a lot of things you can do to minimize your risk with drug use. I'm going to share the following experience in the hope that others will use the information for harm reduction. I did a lot of research before doing this, and it wasn't my first time using alpha-PHP, so please keep that in mind.
For a beginner the most important thing is an allergy test. You should also do one for every single batch of anything you receive, because you never know if your vendor/dealer has given you a different product than before. It may be cut with something or be an entirely different substance altogether that was sold to you by accident or intentionally.
To do an allergy test, take a very, very small amount of whatever it is you're using (in the case of a-PHP I would suggest between 1-5mg at most) and either insufflate it or put it on your tongue, though I must warn you it tastes foul. Wait several hours to make sure you don't have a negative reaction.
Once you're certain you're not allergic, the next step is to figure out the ideal dose and route of administration (ROA). I would not under any circumstances recommend IVing this, even if that's your usual gig. There's not enough known yet about the toxicity of this compound and how much damage it could do to your veins. Some people plug it, some people insufflate it (though it's said to be very harsh on the nose and even likely to cause tissue damage with prolonged used).
My personal method is to vaporize it using an oil burner, also called a freebase pipe but most popularly known as a meth pipe. You could use the dull side of tin foil if you're broke or can't get your hands on proper glassware, but again I wouldn't recommend it. It's too easy to burn and trying to vape it off foil would likely be very wasteful unless you're extremely skilled in this method. Another thing to bear in mind, never use the shiny side of foil. EVER.
Now for dosage ... You need to know your body weight and level of experience with stimulant compounds. The easiest way is to convert your body weight to kg and go from there. If you're not a math whiz, just Google "lb to kg" and a handy calculator will pop up. For a beginner with no stim tolerance or no experience I would recommend using no more than 0.1-0.2mg/kg of body weight.
This is where an accurate milligram scale comes in handy. Don't use one that only measures to 0.1g accuracy. You need AT LEAST 0.01 accuracy, but 0.001 is ideal. They're cheap if you look on eBay, so there's no excuse for not having one if you value your safety.
For someone with experience, but not a regular user, I would recommend the 0.3-0.5mg/kg range. This is what I use, and I've never had a problem. For a heavy user (and I don't recommend this for several reasons) you can go up to 0.8mg/kg. I would advise extreme caution though since so little is known about this substance, and if used too much, too quickly, or too often, it could prove to be very cardiotoxic.
You need to remember to eat, even though the idea will be very unappealing, and you must drink lots of water so you don't get dehydrated. This is important. You should also check your pulse regularly. I usually check mine twice an hour to make sure my heart rate hasn't elevated beyond an acceptable range. The average resting heart rate for an adult is between 60 to 100 beats per minute.
This can be figured by taking your pulse for 15 seconds (I use the timer on my cell phone) and then multiplying the number of beats by four. I find that my pulse tends to stay between 96-100 beats per minute on a-PHP, with a maximum reading of 104 in my sessions. You need to know what the healthy heart rate is for your age. You can find calculators for that online. To find your maxium heart rate, subtract your age from 220. I would advise you to never let your heart rate get anywhere near your maximum. If it does, you need to call 911.
Now you know dosage, ROA, heart rate, and a few other safety precautions. One more thing you need to watch out for is vasoconstriction. Most stimulants cause them to some degree, some worse than others. I only get mild vasoconstriction, even though I also smoke and nicotine is a vasoconstrictor, but some people get it bad. This is where a vasodilator comes in handy. There are all kinds of guides around about vasodilators, and you should familiarize yourself with them and keep something handy in case you need it.
My remedy of choice is a very small amount of 80 proof (40 percent) vodka, around 1/2 shotglass. Be careful you do not take alcohol in large amounts when using stimulants. Not only is this very bad for your organs, but it can actually INCREASE vasoconstriction. A lot of people seem to prefer cayenne pepper for their vasodilator.
I cannot stress enough that you need to be careful with how often you take this stuff. I wait two hours between each dose because I know that's what works for me. If you don't have experience with this compound already, wait longer. Safe trumps dead every time. While I don't condone binging, I understand that it's going to happen, so my advice is to give yourself a strict time limit if you're planning on a binge. Please don't binge for longer than 24 hours or you will likely have some very negative consequences.
If you're naturally prone to anxiety or have a history of getting anxious and/or paranoid while using drugs, then you should keep some benzos on hand. If misused, a-PHP will turn you into an anxious mess. Benzos will help with that and also help with the comedown if you're having trouble sleeping.
I'm not going to go into any great depth with ROAs other than vaporizing. To vaporize a-PHP, place the amount you're going to use into a clean, dry, glass pipe (I find using a plastic straw that's been cut at an angle useful). GENTLY heat the ball of the pipe using a lighter until the drug begins to melt into a clear puddle. DO NOT let the flame touch the glass!!!
DO NOT keep a lighter lit for longer than 10 seconds. It's very, very dangerous, not to mention you could burn yourself. I keep a torch lighter and a minimum of 4 regular BIC lighters on hand for this very reason. The fastest, easiest way is to do the initial melting with the torch lighter (AT LEAST one inch below the glass). Then switch to a regular lighter to heat it up further, and as you're doing so, begin to gently tilt the pipe side to side until you see vapor beginning to swirl.
Inhale gently while continuously swirling the pipe. I switch lighters after every inhale to avoid breaking the 10 second rule (and also because I value my fingers). So be smart, okay? A helpful tip is to make sure your ceiling fans are turned off and that you're not sitting under an A/C vent. Ideally the air around you should be still so the flame won't be battered every which way, thus reducing your risk of burning yourself or your drugs.
I hope this has been helpful and that everyone will heed the warnings I have given.