To know when to use a verb with or without "to" depends always on the verb that precedes it? I am aware that after modal verbs and in imperative sentences the verb is used without the "to", Are there any other reasons for using the verb without "to"?
since you tagged bare infinitives I think the basic form of the verb can be used without to.
I made him laugh
I saw him go.
i noticed somebody come in
He let me go.
I desire that he visit us soon(subjunctive mood)
I hope he comes soon.( simple present)
I suggested that he go( subjunctive mood)
He did go ( emphasis)
He does speak(emphasis)