Si no miras el suelo, puedes tropezar con la alfombra.

Because si no and sino are different things.

• si no = if ... not
  • Si no miras el suelo = If you don’t look at the floor
• sino = but rather / except
  • No es rojo, sino azul = It isn’t red, but rather blue

So in this sentence, si no is correct because it introduces a condition.

Spanish often uses the present tense after si for real, possible conditions.

So:

• Si no miras el suelo, puedes tropezar...
• literally: If you don’t look at the floor, you can/might trip...

This is a normal pattern for general truths, warnings, and likely situations.

Spanish does not normally use the future after si in this kind of sentence. So Si no mirarás... would be wrong here.

Puedes tropezar means something like you can trip or you might trip. It expresses possibility.

• puedes tropezar = you may trip / you could trip
• tropezarás = you will trip

So puedes tropezar sounds like a warning about what could happen, not a definite prediction.

Because Spanish often omits subject pronouns when they are clear from the verb ending.

• miras already tells you it means you look
• puedes already tells you it means you can

So:

• Si no miras el suelo, puedes tropezar...

is completely natural.

You could add tú for emphasis:

• Si tú no miras el suelo, puedes tropezar con la alfombra.

But it is not necessary.

Because mirar means to look at, while ver means to see.

• mirar = directing your eyes intentionally
• ver = perceiving with your eyes

In this sentence, the idea is pay attention and look where you’re going, so mirar fits better.

Here, el suelo means the floor or the ground.

In Spain, suelo is a very natural word for the surface you walk on.
This is especially useful because piso in Spain very often means flat/apartment.

So in Spain:

• suelo = floor/ground
• piso = apartment, and also sometimes a floor/storey or floor surface depending on context

A learner used to Latin American Spanish may expect piso for floor, but suelo is very normal in Spain.

Because tropezar normally goes with the preposition con when you say what you trip over or bump into.

• tropezar con una piedra = to trip over a stone
• tropezar con la alfombra = to trip over the rug

So con is part of the usual pattern.

In Spain, alfombra usually means a rug or carpet laid on the floor.

Depending on context:

• alfombra = rug / carpet
• moqueta = fitted wall-to-wall carpet

So tropezar con la alfombra suggests tripping over a rug or carpet edge.

La alfombra means the rug/carpet, so it sounds like a specific one, or one that is already known from the situation.

Spanish often uses the definite article in places where English might choose either the or a, depending on context.

• la alfombra = the rug
• una alfombra = a rug

If you said una alfombra, it would sound more like some rug or a rug in general.

Yes, you can, and it sounds natural too.

There is a small nuance:

• mirar el suelo = look at the floor/ground
• mirar al suelo = look down toward the ground

In many situations, they are very close in meaning.
In this sentence, both work well as a warning.

Because the sentence starts with the if-clause:

• Si no miras el suelo, ...

In Spanish, when a conditional clause comes first, it is normally separated from the main clause by a comma.

So this is standard punctuation:

• Si no miras el suelo, puedes tropezar con la alfombra.

If you reverse the order, you would usually write:

• Puedes tropezar con la alfombra si no miras el suelo.

without a comma.