i would also (and this is just personal opinion, others may disagree) suggest starting out with DEBIT spreads rather than credit spreads. debit spreads i think are safer for newcomers (compared to credit spreads) because the max risk of the position is paid in its entirety up front, so you're less likely to get into trouble with collateral etc.
getting a feel for your risk in credit spreads will become second nature after a short while, but when first starting out, it is quite possible to get it wrong and wind up overextending your trading account.
in my opinion the main focus when first starting out in options should not to be to make the max profit possible, but rather, it should be to make sure you don't blow up your entire trading account during the learning process. something that is very easy to do with leveraged derivatives if you're not careful, especially with IB where there is no level 1, level 2, level 3 etc. permissions, like there are with some aust brokers, that function to restrict the types of strategies you can do. in contrast, as soon as your IB account has options trading approval, they give you all the toys to play with. yes, they will let you sell a naked call (if for some unfathomable reason you actually wanted to do that) provided it meets the initial margin. i know this for a fact, as when i was first starting out in options, i crazily tried to leg into a call spread by going for a fill on the short leg first, as i thought the underlying was about to "ease off a bit" and i could get the long leg filled more cheaply. so i essentially had a naked call for several very uncomfortable minutes as i watched the thing keep rallying. never again. free tip - DON'T DO THAT!
so yes you get all the toys straight away at IB but it's a double edged sword because as soon as you fail to meet your margin requirements - and they calculate that in real time, not just on an end-of-day basis - as sails said, you're given a few minutes notice before they start closing down positions randomly. so you must be careful and IMHO sticking to debit spreads, at least at first, is one way to do that.