Infinitive + ending
Regardless of whether it's an ar/ir/er verb, the endings will always be the same. It's just important to look out for the irregulars.
There are many irregular future/conditional words in Spanish, and they are the same in both tenses.
A small number of Spanish verbs use a modified version of the infinitive for the future. There, they usually add a d.
oír → oiré
If the stem of the word is irregular, the compound word will be too. For example poner is irregular, so componer will behave in the same way. This works for all words with irregular stems.
In addition to it being used as referring to the future, it can also be used as "probably". For example, you can say "Serán las ocho." which would mean "It's probably eight o'clock."
Here, the conjugation is essentially the same as the future. The rules are the same, and the ending is the only thing that changes.
The irregulars are exactly the same, which makes the conditional a lot easier.
The use of the conditional tense is mainly used as the world "would".
Me gustaría tener un coche caro. (I would like to have an expensive car)
Juan dijo que iría. (Juan said he would go)
This is also used with si + imperfect subjunctive
Si pudiera, haría, pero no puedo, así que no haré. (If I could, I would, but I can't, so I won't.)
This is also used as the word "probably" sometimes (LESS OFTEN THAN FUTURE).
El niño tendría nueve años. (The kid was probably nine years old).