～し

し is kind of like the て form in that it functions like “and”. However, there are things left unsaid with し。

And

And (Things left unsaid)
Verb/い Adjective + し
Noun/な Adjective + だし

Since し leaves things unsaid, it can be used to make an incomplete list. Typically used with adjectives, but verbs are allowed as well. 

• 先生は優しいし、頭がいい – The teacher is kind (and stuff) and smart. 
• 彼女はきれいだし、声も美しい – She’s beautiful (and other stuff) and her voice is beautiful.
• 彼はなまけものだし、最低だ – He’s lazy (and other stuff) and horrible. 
• 寺にも行ったし、ホテルに泊まった – We went to temples (and others), and stayed in a hotel. 

There is a strong tendency to use も in place of が or を in this pattern. 

• 食べ物もおいしいし、値段もいい。- The food is also good (and other stuff) as well as the price. 
• 人もいっぱいいるし、行きたくない – There’s a lot of people (and other reasons), so I don’t want to go. 

Reasons

The most common use of  し you will see is to list more than one reason. Using し implies that the reasons listed are not all of the reasons. 

• 行きたいし、時間もあるし来週に行く – I want to go and I have money, so I will go next week.
• 彼が好きだし、時間もあるし、行きたい – I want to go because I like him and I have time. 
• 猫が好きだし、食べていなかったし、猫カフェにいった – I like cats and was hungry, so I went to a cat cafe. 

し can also be used to imply a reason that you don’t want to say/can’t say. 

• お客様がいないし, ねます – There’s no guests (and I’m tired) so I’m going to sleep. 
• もう終わったし、帰ろう. – It’s over (and I have stuff to do), so let’s go home.
• 降りそうだし、やめよう – It looks like it’s going to rain (and I don’t want to) so let’s not do it. 
• しょくばが好きだしやめない – I like my workplace (and the salary), so I won’t quit.

You may also change the last し into から (for reasons)

• 忙しいし、疲れているから行かなかった – I was busy (and other stuff) and tired, so I didn’t go.

See also から

し vs から

Since し does not name a specific cause it generally comes across as softer than から。
から on the other hand is direct and to the point at naming a specific cause.

• 猫が好きだし、行く – I’ll go because I like cats (and other reasons). 
• 猫が好きだから行く – I’m going because I like cats. 
• 猫が好きだし、暇だからいく – I’m going because I have time and I like cats (and other things). 

VS て and たり

• 先生は優しくて、頭がいい – The teacher is nice and smart. 
• 先生は優しいし、頭がいい  – The teacher is nice (and other things) and smart.
  
  
• 忙しくて、疲れているから行かない – I won’t go because I’m busy and tired. 
• 忙しいし、疲れているし行かない – I’m busy, and tired (and other reasons) so I won’t go.
• 寺にいって、ホテルに泊まった – Went to a temple and stayed at a hotel.
• 寺に行ったし、ホテルにとまった – Went to a temple (other stuff too) and stayed at a hotel.
• 寺に行ったりして、ホテルにとまった – Did things like go to temples, and stayed at a hotel. 

See also たり