Keyword research - long tail or short tail

Hello,
To be honest I am new to this so I'm terribly sorry If I am posting this to the wrong sub-forum. I am trying to learn as much as possible about kw research and I believe I have read most of the useful tips on the internet but what I'd like to know now is (according to your experience) - Do you rather use 'long tail words' or short ones.
Long tail is an expression for words that could pay out in some longer period of time and eventually would 'last' longer.

Long tail keyword has nothing to do with payment over a period of time. It is just a longer keyword than other keywords. For example: the keywords "dogs" is a main keyword then there is "dog houses" and "pet stores for dogs", these are long tail keywords. Generally, they are easier to rank because they have less competition, but they also have less traffic as well.

Okay thanks, well as I said I am kinda novice.. So what words are preferable?

Try and think of phrases that people would type into a search engine, then see what competition this keyword has. Also if you get a domain name that matches your keyword then it will help you get ranked quicker.
There are lots of SEO / Keyword guides on here which will help.

Any words which are searched for and have little competition are the best. For example, your main keyword might be "dog training". Then you can write a bunch of articles with long tail keywords such as "dog training for puppies" or "best methods for dog training". Simply search your main KW in Google will give you a list of long-tail keywords that you can also target (these are at the bottom of the page)

To get to the top instantly use long tailed keywords as they will tend to have lesser competition. Once you get to the top you can then focus on the more difficult short tailed ones.