Paranormal investigating is not like you see in the movies or on t.v.. Far from it. Instead of finding great evidence immediately or over a two hour period, one can spend eight or ten hours alone or with a group , and find nothing of value. Of course, you can scare each other accidentally or on purpose and believe that this is a personal experience.
Now that the understanding of immediate gratification is probably not going to be the case, you can continue with the actual basics of being a paranormal investigation. The most important would have to be a very intense passion bordering on love for the whole field. There will be times when the manta , "why am i doing this?" will fill your mind as you stare at monitors hoping something will move, or an apparition will appear.
Solitary investigating is definitely out of the question for obvious as well as arcane resons that would take a book to cover. Always have someone with you or be part of a group. That way , if trouble arises as it inevitably does, there is help close at hand. Examples of this would be, getting hurt, scaring yourself, or even forgetting to turn on pieces of equipment. Having a friend or co-investigator to corroborate personal experiences always goes farther than a supposed 'fish story'.
Covered so far has been spending long hours in the dark, usually in creepy, but not necessarily haunted spaces, and having a partner just to be there, as well as validate experiences. Having the right equipment as your experience grows is probably the next important component. A video camera with infrared capability for now is a must. If electronic voice phenomena is to be believed, spirits prefer the darkness.
It somehow facilitates the transfer of energy that they need to actually make a noise, move an object, say something or even show themselves. So until something can be found to ease the problem of stumbling around in the dark, infrared handheld video recorders allow one to navigate the darkness through a 3" by 3" screen while documenting by video , all that is seen at least.
A small 12 led or more flashlight is great to have, especially when changing tapes in the video recorder, or other unexpected oddities that happen. Sometimes, that night vision just gets to you and there needs to be a break. This , as well as a partner may save a very painful experience of dry rotted ceiling and eight feet to go till the floor.
The last for basics at least would be an emf detector. There are many good ones on the market and without delving into the pros and cons of each one here, just about any one will suffice for the beginning paranormal investigator.