Only cards that are activated that have a spell speed can be chained to. Though we often say things like I-chain-to-your-attack, or I-chain-to-your-summon we are actually just responding.
I can write a list of for you of the cards with spell speeds. This list can also be found inside of any playing manual.
Spell speed 1:
Normal Spell
Continuous Spell/Trap:You can chain to its activation, But like the guy above me said, these ones can be tricky, and you will need to check out certain cards to see if their effect is continuous or if or if has activation effects.
Equip Spell: This one can run the same way as a continuous magic card, most can only be chained once activated, but some have effects which can be chained to.
Field Spell: These ones can pretty much only be chained to at activation, I do not know of any field cards effects that can be chained to except Harpies' Hunting Ground. If anyone else knows any more, or if it is even possible to chain to that one I would be glad to be corrected on it.
Ignition effects: Cards like Exiled Force and Breaker the Magical Warrior can be chained to.
Continuous Monster Effects: Once again, this is something I am not 100% sure about, but I do not know of any monsters that have continuous effects that can be chained to.
Flip effects: Yes these can be chained to
Spell Speed 2:
Quick play Spell: These can be chained to as well
Normal Traps: Chainable
Multi Trigger Effect Monster: Cards like Maryokutai or the A-Team Trap Disposal ( is there anything those guys dont do?)
Spell Speed 3:
Counter traps: Sure it can be chained to, but I cannot remember the last time I saw Seven Tools of the Bandit. Plus for your purposes it does not really apply since you cannot chain quick plays to them.
Good Luck.
:edit: I forgot to add in "traps" to that whole continuous bit. No need to forget those. those are more prevalent than the contiuous magic anyway.