I'd try and combine bjj with kick-boxing. That way you train stand up and ground fighting skills. I started half a year ago and tried a lot of different things before finding what suited me best. I take jiujitsu lessons twice a week and kickboxing lessons once a week and I do MMA-training. The best thing to do though I think is try and master one form of martial arts first, preferably one that focuses on both stand up and groundfighting like jiujitsu.
And if you can take classes with experienced MMA-fighters who don't mind adjusting to your level, do so, because you can learn a great deal from them.