If you read names from popular novels you feel like the names define characters. They fit perfectly to the personality of character. For an e.g. Harry Potter, Robert Langdon, Jason Bourne, etc.

I have a character who is a professor of psychology, is chubby, easy going, interested in mystical things. I named him Rufus Drake...Rufus is name of my friends son, Drake I took from Professor Shaledrake. But then as I write I discovered it sounds highly pretentious. Like a vampire novel, which I am not writing. So I changed it to Michael Brown, which I believe to be a realistic sounding name in the UK. I also tried different last names of my English friends but its not giving justice to my character.

I also have a French guy as a character. I named him after my friend but the last name I just made a Google search of French last names and it sounds pretentious.

I also have to design email ID's and gaming zone names for these characters.

I am asking what's this art of imagination? Can something be done or do I just have to practice?

Have more faith in your process, but run it by others.

Rufus Drake is a great name. It has personality, it's easy to pronounce and it's memorable. It's not uncommon but the combination isn't going to be used much. There's nothing wrong with the name Michael Brown. I bet the million other Michael Browns agree. It's awfully generic though.

Google and research and use your friends for inspiration. Those are all good approaches.

Once you have your names, use them a while to see if they sit well. Google them to make sure they're not famous (or infamous) people or other known characters (pretty much all names will exist in real life and/or in fiction, so don't worry about that, just avoid known ones or full names that match people you know personally).

Now run them by your critique group, beta readers, friends or family. If anything stands out as weird, you want to know earlier rather than later.

For names from a culture other than yours, run them by people from the culture you're using. If you're not French, for example, do a check with a French friend to make sure the name you choose sounds plausible. Google and other searches help here too; if there are people with that name (or the given and then the surname) on Facebook, for example, and they're from your target country, then you know it's a legitimate name.

For screen names of various sorts, try to avoid duplicates of existing names if the name is anything more complex than John54. Those will be part of the personality of the character, but a lot of people choose names that were suggested by the application or were a joke or had meaning 10 years ago and stuck, so don't overthink it.

Sometimes it's best to just throw names out and see if they stick. Working too hard on it can lead to the paralysis you are experiencing. Check them later but create them quickly. After a while, your intuition will kick in and naming will be easier.

TL;DR

No need to worry: when you write a good story, any name sounds great.

Good names are as good as the story

Good unique names are not easy. In particular, it is not easy to come up with a good fitting name before having the whole story laid out. On the other hand, most of names however sound great not because of the name itself but because of the character bearing it.

To give an example, Harry Potter is a very simple name. It could have been John Corker, or Fred Horseford. Even Michael Brown. It sounds great and unique because Harry's story resonates with the reader.

Get to know your character, you'll love the name

If you start writing your story, it is quite possible that at the hundredth iteration of spelling out "Michael Brown" you may find that such name was befitting of the character after all. In fact, over time you have become acquainted with him, and Mr.Brown is not anymore just two silly sounding words put together, but a character with a past, a story ahead, goals, desires, conflicts, and all that makes him interesting.

Rufus Drake is equally a good name. The choice of less common words often makes it easier to jump start with a positive attitude towards a character. The feeling of such name being pretentious is actually more a feedback about the story than about the name. In other words, the story may be duller than expected and Rufus is not living up to the expectations: raise the stakes, increase tension, add conflict.

A note on naming systems

Given the above, having a naming system can save time. A naming system is a set of rules that can help you quickly generate names that look and sound from the same place.

For instance, you could stick to the first- and family-name naming convention, and use colors as the first name, and a combination of tree names and tools for last names: Red Birchsaw, Blue Oakhammer, Gray Pinerake, etc...

As an anecdote, I recently came across two animes: in the first the characters from the alien world had names of cocktails (princess Pina Co Lada, knight Beefeater, Shandy, etc...); in the second, one character had to name a clan of goblins and went for Gob-something (Goba, Gobu, Gobaz, etc...). These are obviously silly names per se, but in the context they quickly stick to the characters and it becomes natural to hear/read them without laughing.

Here's a system I use for main characters or characters that must have the 'perfect'name:

1. choose a language (English, Chinese, Spanish, etc)

1.1 decide whether to apply the same language to both first name and surname or use different languages (if in a cosmopolitan country, usually)

1.2 make sure you understand naming conventions of the chosen language (Portuguese can have up to 2 first names and 3 surnames; Japanese have surname first then the given name; Spanish have first name + father's surname + mother's surname; etc)

2. Meaning, explicit and implicit

2.1 you can have an obvious meaning (Autumn), a hidden meaning (Sarah = princess) or no meaning.

3. sounds (this may be more important than meaning for the character)

3.1 choose a majority of strong sound (e.g. with p, b sounds) or soft sounds ( e.g. with s, l, sounds) or an appropriate mix

3.2 you can choose an abundance of consonants or vowels (Fred vs. Ayden), keeping in mind that vowels tend to be softer and gentler in sound than consonants

3.3 when working with vowels, check if you prefer open ones (as in cat, hot, pet) or closed ones (as in put, pit, look, leet).

Now, start making a list of names and a list of surnames. Mark the ones you like, the ones you dislike and the ones that are ok. Erase the ones you don't like.

Start combining favourite first names and surnames, and then also mix some of the ok names/surnames. If the character is to have two first names, try first deciding which two go together before adding the surname to the mix.

I strongly suggest that you end up with half a dozen possible names, even if you fall in love with a particular combination.

Now you have two options, you can either poll some friends for which name they prefer, or you can write a short chapter and copy it half a dozen times, each one with the different candidate. Try to make the chapter heavy on using the name in different situtions (eg: start at home with family, stop by the cafe where they're well known and come across a friend, then talk to several work colleagues before meeting the boss, etc).

Put the chapters away and wait a couple of weeks. Re-read and choose the one that sounds more like the character (personality-wise).

Note that this is a time cnsuming approach best reserved for one or two characters per novel at the most. You can also feel satisfied with choosing one name from the half a dozen candidates and call it a deal.