Advice from a bootstrapped/non-funded entrepreneur. If you have funding or are scaling extremely quickly maybe none of this applies:
* don't hire anyone to do work you have not personally done. You need to know how long it takes and what kind of effort is involved or else on-boarding is difficult.
* unless your startup has revenue and is profitable, don't pay someone a higher salary than you are getting. Doing so can breed resentment on your part.
* don't offer equity if you can avoid it: no-one else thinks your company is as valuable as you do anyway.
* don't get hung up about a CS degree unless it is necessary for the work. For most web-development you need someone who is SMART and ENTHUSIASTIC, and who is a fast-learner with a track record of getting stuff done and an interest in web-development. Plenty of liberal arts majors have these skills.
* someone should know about 80% of what they need in order to be fully productive. This means you shouldn't sweat stuff like knowledge of MVC or particular frameworks. This is where the fast-learner and enthusiasm bit comes in, and it can be a good excuse for setting up a probationary period.
* interns have always ended up being more work for me than they are worth when asked to work independently, but if you are willing to spend time supervising and can work closely with them in a way that ties closely into your own workflow (I am working on X and need Y done now) they can be a real effort multiplier.
* if you can afford it, pay people well. This is not always possible, but it is so much easier dealing with someone who is paid decently, because they won't feel taken advantage of and will more likely give you the benefit of the doubt when you start freaking out under pressure or act poorly because of stress. Not that you should do this.
* finally - CANNOT STRESS THIS ENOUGH - in the event of conflict, you need to deal with it personally in one-on-one conversation rather than through email. This avoids miscommunication and keeps both sides from internalizing grievances.