～たり～たり

たり form
Plain Past Tense Verb/Adjective/Noun + り
Things like X and Y
XたりYたりする

The たり form of a verb means “Things like”. It’s useful for describing general types of things you did or might do.
It’s typically used with multiple verbs, but may be used with just one.
You must* use する after the final たり. 
Nouns and な Adjectives use だったり/じゃなかったり.

• 食べ物を食べたり、話したりした – We did things like eat food and talk.
• 家に帰ったら本を読んだりテレビを見たりする – When I get home, I’ll do things like read and watch TV.
• 友達と遊んだり、ゲームしたりした – I did things like play with my friends and played games.
• 家で掃除したりする – Do things like cleaning at home. 
• 人だと思ったかげは、クマだったりする- Shadows I thought were people would turn out to be things like bears. 

Back and Forth

Sometimes X, Sometimes Y
XたりYたり (Opposites)

たり can be used with opposites to express that things went back and forth between two states. Typically this is used with the weather.

• 暑かったり、寒かったりする – Sometimes its hot, sometimes its cold. (its hot and its cold).
• 彼は優しかったり、厳しかったりする – Sometimes he’s nice, sometimes he’s strict.
• 人があったりなかったりする – Sometimes there’s people and sometimes there’s not. 
  
  

たり and する

As mentioned above, する should be used after the final たり in a sentence. However, particularly in songs or longer sentences, Japanese people forget or intentionally omit the する。It’s commonly forgotten in spoken Japanese, however, You should make it a habit to use する.

• トイレに行ったり、ご飯を食べる時間もない。
   I (did) things like go to the bathroom and didn’t have time to eat. 
  This is passable, but should really be トイレに行ったりして、ご飯を食べる時間もない

Sentence pulled from the NHK (additional reading)