I do not suggest oral. Results with oral dosing seem inconsistent. I have not personally attempted it because I feared wasting what little I had. If you do take it orally please let us know how it goes but I suggest avoiding that ROA. Most people that have used it more than myself say IM is more gentle and the proper way to go for breaking through but again I do not suggest that ROA because it requires use of a needle and without proper technique you could be setting yourself up for infection. My personal rule of thumb is to never involve needles, mainly because I'm scared of them but also because I do not trust myself to use them properly and fear that I might start attempting to IM/IV other substances if I ever started.
My experiences with DPT used the following ROAs: Snorting, Plugging, and smoking/vaping freebase.
-Snorting: Snorting is how I broke through. For consistent dosing I would suggest this ROA. It's very hard on the nose and the drip is awful and will distract you during the first part of the trip but it seems to be the safest way to breakthrough without involving needles. I can't give dosing advice but I will say this: I would keep it under 100mg for your first time. If seeking the full breakthrough prep your dose and split it into at least two lines or four small lines. Time will become meaningless very quickly. While DPT doesn't have a very long duration compared to other substances I've taken while you're in the middle of it you'll find yourself questioning if it'll ever end and thinking it has been working on your for far longer than reality. 20 minutes can seem like hours. Also, once you come-up it'll rocket to peak almost instantly. If you're interested here is a trip report I wrote about my breakthrough:
http://www.bluelight.org/vb/threads/776463-(DPT-120-140mg)-First-time-I-am-a-mouse-among-giants
-Smoking: As said before convert it to freebase and smoke/vape it like you would with DMT. Smoking the salt does work but you will waste a good bit of material and it's very harsh if you don't convert it to freebase first. This ROA is good for working up to a proper dose. I never broke through with smoking because I was a bit scared of it by the time I started attempting this ROA and was seeking sub-breakthrough doses. It's easy to go too fast and get too out there with this method and you'll know instantly. I suggest using a lightbulb/methpipe if you're going to go with smoking the material. Just take it slow and leave a good 10-15 minutes between attempts. Keep the doses small as well. Don't attempt to breakthrough all at one time.
-Plugging: I did this ROA in the hopes of avoiding the problems with snorting. The material did burn a bit and I quickly abandoned my attempts using this ROA. I didn't have much material to work with at this point and was mixing it with MXE. I don't have much advice with this ROA beyond that sadly.
No matter how you attempt it be very careful with DPT and show it the utmost respect. It will bite you if you disrespect it. It's nothing like DMT and you will/can be up and mobile during the experience. During my breakthrough being inside seemed to put me in a bad mindstate even though I was in a setting where I normally had a good time. DPT seems to be better in nature (at least for me) and I would suggest doing it outside on a warm day in a place where you don't have to worry about being around anyone else/the public. DPT isn't a substance you can really control either. You're going to see and think about things that may scare/bother you. For me the experience always showed me bad things about myself and provided me with a lot of things to work on/change about myself. I do not consider DPT to be a substance I could ever do just for fun or on a whim. DPT is for serious work and exploration of your own psyche. That said, there is a good side to it near the end of the trip where you can obtain a state of peace similar to where DMT tends to put me. Every experience I had with DPT was like having lighting bolts thrown at me by God himself. It has a heavy body load that causes your entire body to vibrate/spasm. This can be a bit worrying even if you're expecting it. Every time I took it I would almost instantly question why I'd taken it and would usually swear off all drug use for some time afterwards. It's instantly self-limiting.
One last thing: DPT has a very religious vibe to it. If you don't believe in God you might find yourself begin a devout follower of religion very quickly. This is normal and has been the experience of most people I've spoken with that were atheists going into the experience. Keep an open mind and don't be surprised if this happens to you as well. There is a good reason why certain churches consider this substance to be the flesh of Christ.
Set and Setting are more important with this substance than any other substance I've taken. Do not take it in a party environment or casually the first time. Make sure you're in a safe place, make sure you trust the people you're with. I would actually suggest not doing it with a group and would limit it to just a trusted trip sitter. I did it alone when I broke through. You'll be able to take care of yourself even if you breakthrough and if you're a private person like myself you may not want anyone around to see you during the actual trip. The wisdom on BL is to always have a sitter though and it's probably a very good idea if you aren't experienced with other substances. Just make sure you *really* trust them because you're going to bear your soul during the peak to whomever is nearby at the time. Make sure your sitter is aware of this and the fact that the body load caused by DPT can induce full-on body spasms. Your back may arch and you will find yourself unable to control your body at some points especially when you're first coming up. It's like electricity is running up and down your spine. I laid in bed for a long time just attempting not to shake and couldn't stop. I ended up having to direct that energy into something else. I found that walking/hiking out in nature really helped to calm down the body load.
The drip smells/tastes like burnt rotten pussy. Your nose will burn badly if you snort it. Do not be surprised if it bleeds a bit too. Mine had caked up blood in it the next morning. The drip is distracting for sure. It isn't as bad as snorting a 2C substance but it's close to that type of pain. I still think that's better than involving needles but I've heard from people with more experience than myself that using the IM ROA avoids some of the body load. I still would suggest not involving needles even with the horrible drip/body load. I don't think you can tame DPT no matter what ROA you use.
All that said: I would repeat the breakthrough. DPT basically saved my life. I would have probably ODed on opioids a long time ago if not for that breakthrough many years ago. DPT also caused me to accept religion into my life which has made me a better person. I'm a better person for having done it. I'd be content with never attempting it again. I may use it 2 more times before I die but I don't plan on taking it again any time soon.
Best of luck. I hope this was helpful in some way.