Stationariesery

There is no plural form of the word "stationery."

One of my favorite hobbies areis visiting stationaery stores

how to remember the difference:
a) stationEry = We buy stationEry to write a lEtter
b) startionAry = When we stAnd still, we are stationAry

There, I buy things or site seeing wheneverbrowse for things I want.

Unlikely other people, I usually use fountain pens more than 7in 7 different colors.

I also use a fountain to write.

Because, ink hais a lot of water than ballpoint pens, so the papers are also important for using fountain pensiquid, which paper to use use is also important.

For arranging my idea, Index cards are good tools.

For arranging my ideas, index cards are good tools.

Of course, for the cards it's possible to use pens.

LikeFor this, there are many things in the stationary shop are waiting for me.

Stationariesy

"Stationary" refers to all instruments used in writing in general, it doesn't take plural usually.

One of my favorite hobbies areis visiting stationary stores

"One ... **is** visiting stationary stores"
You can think of "one" as the subject here, part of the group "my favourite hobbies". Because of that "is" will be singular.

There, I buy things or site seeingbrowse whenever I want.

"Sight-seeing" is usually used for seeing things when you visit another city/region or country. If you're looking around a store 'look around' or 'browse' is better.

Unlikely other people, I usually use fountain pens more than 7 colours of fountain pen.

Some suggestions: "I usually use multicoloured fountain pens" or "I use many colours of fountain pen together."

NI am interested in new pens and inks with beautiful color are my interesturs.

"are my interest" isn't really a natural way to show interest in English.

Because,Since ink has a lot ofmore water than ballpoint pens, so the papers arepaper is also important for using fountain pens.

1. "sine" is usually used when you want to emphasise the other part of the sentnece.

2. I put "paper" in the singular here because most people *in this context* would use it as a "mass noun" (like "water", "bread", etc), instead of a "count noun", like "three/four/five papers".

For arranging my ideas, Index cards are good tools.

Of course, ithe cards is possible to use pens with the cards.

Lastly, diaries are very important tofor storeing my memorierecollections and my records.

1. Most people would use "recollections" here instead of "memories", since that usually refers to the version in your head, :p

2. "my" can be used once for both words here

LJust like this, many things in the stationary shop are waiting for me.

1. "Just like ..." is a more natural way to say this.

2. "are waiting for me" is totally fine, but this expression sounds less humanizing, in case that's what you were going for.