Well as literally every serious person on this site would tell you, it's not as easy as just finding a spell and trying it out. You need to practice a lot of other things. Also, a good 80% of the "spells" on this site are absolute bull, so your best bet would be to make one up all on your own.
My tips, use what seems to get your energy flowing by speaking/ reading it, also it is often good to tinker with one's own ideas. it is best to start out magic with learning the intricacies of oneself.
P.S. steer clear of the "Fantasy Spells" section, it consists of four elements: fluff, fanservice, screwballs and sparkles.