Volitional form + と思う: express an intention
Build forms such as 読もう and 食べよう, then use context to distinguish a resolve voiced to yourself, an invitation to someone else, and an intention stated with と思う.
Form the volitional by verb group
For group 1, use the o-row sound plus う: 読む → 読もう and 話す → 話そう. For group 2, replace る with よう: 食べる → 食べよう.
する becomes しよう, and 来る becomes 来よう（こよう）. Learn the pronunciation of 来よう along with its spelling; it is not きよう.
Identify whose intention is expressed
週末は図書館で勉強しようと思います。 expresses an intention to study at the library this weekend. 一緒に勉強しよう。 instead invites someone to study together.
勉強しようと思っています。 presents an intention the speaker holds. It often suits an existing plan, but the distinction is not a fixed number of hours or days.
An intention is not a confirmed booking
来年、日本へ行こうと思っています。 does not establish that dates or tickets are settled. Add those facts when you need to communicate a confirmed arrangement.
Choose one thing you intend to do today and form its volitional. The volitional of 習う is 習おう; keep it separate from the ongoing state 習っています.
Quick check: How do you combine 読む with the volitional and と思います?
Show the answer and why
読もうと思います. 読む is a group 1 verb, so its volitional is 読もう, not 読みよう.