saki ni yomu ni kosita koto ha nai.

先に means first, beforehand, or ahead of time.

• 先 = ahead, previous, earlier
• に turns it into an adverbial expression

So 先に読む means read first or read in advance.

Exactly how you translate it depends on context:

• read it first
• read it beforehand
• read ahead

In 先に, the particle に is making 先 function adverbially.

This is very common in Japanese. It is similar to saying:

• 早めに = early
• 前に = before
• 後で = later / afterwards

So 先に is not a separate mysterious grammar point here; it is just the normal way to say first / beforehand.

That に is part of the fixed grammar pattern:

dictionary form verb + に越したことはない

So here:

• 読む = to read
• 読むに越したことはない = there is nothing better than reading / it is best to read

This に does not mean to in the usual direction sense. It belongs to the expression に越したことはない.

It is an idiomatic expression meaning:

• there is nothing better than ...
• it is best to ...
• you cannot do better than ...

So 先に読むに越したことはない means something like:

• It is best to read it first
• There is nothing better than reading it beforehand

The nuance is often that this is the safest, wisest, or most desirable option.

越した comes from the verb 越す, which can mean to go beyond, to exceed, or to surpass.

So literally, に越したことはない is something like:

• there is no thing that surpasses doing X

That literal meaning is why the natural English sense becomes:

• nothing beats doing X
• it is best to do X

In modern Japanese, learners should usually treat に越したことはない as a set phrase rather than trying to translate each word literally every time.

Great question. 越した is the past form of 越す, but in this expression it does not make the whole sentence past tense.

This is just how the fixed expression is built:

• に越したことはない

So even though 越した looks past, the overall meaning is present/general:

• it is best to...
• nothing is better than...

In other words, this is an idiomatic grammar pattern, not a literal past-tense statement about something that already happened.

こと turns the idea into an abstract thing / matter / fact.

In this pattern, こと is part of the set expression:

• に越したことはない

You can think of it roughly as:

• There is no better thing than doing X

But in practice, it is better to understand the whole phrase as one chunk instead of focusing too hard on こと by itself.

Here は marks こと as the topic and gives a contrastive/emphatic feeling.

Very literally:

• As for a thing better than that, there is none

That is why the full pattern means:

• there is nothing better than...

So は is not doing anything unusual by itself, but it is part of the standard form of this expression.

Yes, very possibly.

Japanese often leaves out information that is obvious from context. Since 読む usually needs something to be read, the object is probably understood already.

For example, depending on context, it could mean:

• read the instructions first
• read the book beforehand
• read the materials in advance

So the sentence is grammatically fine even without stating the object.

Yes, it is natural, though it sounds a little more formal or written than a very simple everyday suggestion.

A more casual, straightforward way to say something similar would be:

• 先に読んだほうがいい = You should read it first

The difference is nuance:

• 読んだほうがいい = it would be better to read it first
• 読むに越したことはない = nothing would be better than reading it first / ideally, you should read it first

So に越したことはない sounds a bit more like a firm recommendation about the best option.

Yes.

It can be used with nouns too. For example:

• 健康に越したことはない = Nothing beats good health

With verbs, you use the dictionary form:

• 早く行くに越したことはない = It is best to go early
• 先に読むに越したことはない = It is best to read first

So this is a useful general pattern, not something limited to this one sentence.

The polite version is:

先に読むに越したことはありません。

The meaning stays the same. The only difference is politeness:

• ない = plain
• ありません = polite

So you may see both:

• に越したことはない
• に越したことはありません

Both are correct.