I would take it no other way than orally, and then I'd suggest 6.25 mg (half a tablet) if you are looking for a nice boost in mood and energy w/ some good euphoria. If you don't plan on using Adderall that often, you could go ahead and do 12.5 mg, but it will result in a stronger high with a great deal of energy (possibly scattered and rampantly shifting focus, instead of improved focus on lower doses - but this varies), more euphoria, and a higher chance of side-effects which would be more severe in degree (e.g. anxiety, panic, physical "jitters" and/or tension etc.). So, if you want a nice high (you WILL feel it with no tolerance) that probably won't be TOO much, I'd suggest trying 6.25 mg (half a tablet) orally. If you want a really speedy and "rushing" high, with the possibility of more anxiety and nervousness (including during comedown) and other side-effects, you could try the 12.5 mg. It is not really unsafe - the 12.5 mg Adderall IR for someone with no tolerance, if you are in good health and such, but I think 6.25 mg do you good at that dose. Drinking on amphetamines is not the best idea, for you could consume too much alcohol which won't sedate you as much initially, until after the Adderall wears off and the alcohol could potentially be TOO much - that is dangerous. Also, both can result in dehydration on their own, and together would likely cause a good deal of dehydration, and this could lead to an especially nasty hangover/comedown combination, which I can just imagine being VERY unpleasant. So, I'd suggest you take the Adderall without alcohol or any other drugs which you are not physically dependent on. If you are taking other drugs or scripted meds, whatever they may be, they could have an effect on the Adderall experience and the safety, so please say if you are for the best possible harm reduction with best recreational result.
Oh, and with amphetamines, ALWAYS keep hydrated - you will feel thirsty, and just know. I don't really mind that they take away my appetite, because they do for nearly anyone, esp. without a tolerance, but that is my personal preference, and I would recommend making sure you have at least a little something to eat before or during the Adderall. An empty stomach, however, allows for better and more speedy absorbtion of the amphetamines into the blood, which equals quicker onset. Be safe, and know your shit, and have fun. But, please don't drink with the Adderall!