It really isn’t. It’s a very good and thoughtful question 
Totally reasonable; it’s very different from summoning demons. Unless you are evoking them into your temple.
It’s good form to introduce yourself (name, ancestors, birthplace, lifestyle, intentions, interests, spiritual allies). It’s also good to leave (culturally appropriate) offerings; definitely don’t collect graveyard dirt without asking and leaving offerings. Liquid libations, coins, flowers, cakes, fruits.
It’s helpful to actually spend time at the cemetery. Meditate and talk with them; ask them what you can do for them. Look into the history of the cemetery, make art about the spots that pull you in, and make a note about which graves seem to attract you.
It’s good to have a relationship with a psychopompic / necromantic entity. Hekate, Bune, Hel, Hermes, Murmur, Nergal, Azrael, etc. Not all of the dead are nice and it’s good to go in with some authority, in case you need it. They can also help you build bridges, attune to the energies, and facilitate communication.
You could bath in necromantic herbs before heading to the cemetery (mullein flowers, wormwood, dandelion, poppy, etc). It’s not necessary but it helps. Dropping tinctures / applying ointments can help, especially with (safe doses of!) henbane. Tinctures are fairly easy to make on your own, but will take time to make. They are fast-acting. Ointments are more complex to craft and can take many hours to “kick in”.
If you would like to use tinctures / elixers / oil infusions / ointments with poisonous plants such as henbane, Belladonna’s Botanicals and Banefolk are reliable and high-quality providers. Harold Roth offers a short and affordable online course about henbane which includes recipes for tinctures and ointments. I enjoyed and recommend the course.
I also make offerings at home and invite them to come to me in dream. A few have taken me up on the offer.
@norse900 is very experienced in working with the dead. I think the most experienced on the forum. Check out his journals!
@Arianna has an interesting thread involving (respectful) graveyard adventures that you may enjoy reading as well:
This video has some more advice:
