Invitee - implied or express invitation to enter and/or remain, mutual benefit, public or business invitee, duty to inspect land for danger, duty to make safe and warn of dangers that are actually or constructively known (although warning might not be enough), also typically imposes special duties such as duty to rescue while on premises.
Licensee - implied or express invitation to enter and/or remain, benefit primarily rests with guest, typically has to do with social guests (people visiting your home, etc), no duty to inspect, duty to make safe and warn of dangers that are actually or constructively known
Trespasser - no express or implied permission to enter and/or remain, basically the only duty is to not wantonly or willfully injure, although you'll run into exceptions to known trespassers, e.g., and may have to warn about artificial conditions on the land that could foreseeably injure, etc.
Also, keep in mind that some jurisdictions have done away with the invitee/licensee status and just impose a general duty of reasonable care to people on the premises with permission to be there (I think some states may have gotten rid of all three distinctions; it never came up in my class).
I don't really know if there are any tips other than just knowing it - it's not that difficult.
When you see a business customer or somebody who entered land that is generally held open to the public, think invitee and duty to inspect/warn/make safe
When you see a social guest, think licensee and duty to warn/make safe
When you see somebody with no permission to enter/remain, think trespasser and duty to not willfully/wantonly injure
Also, Rowland v. Christian eliminated all three and simply impose a duty of care to warn everyone of possible dangers while Heinz v. Webster County abolished distinction between licensee and invitee.
Not sure about which states follow which though.