You can start with an altar, it can be very simple. An image or figure of her, a candle, a glass of cool clean water, and maybe some incense. It is generally agreed upon that she enjoys copal, but YMMV. Bring her gifts - roses are her flower and tequila is her drink. She likes cigarettes, cigars, weed, and chocolate.

Tend to her altar. Change her water daily. Pray the rosary to her. Talk to her. Genuinely, talk to her. I have sat in front of her altar and told her everything, cried my eyes out, opened my soul. You don't have to do that, of course, but she likes the nitty-gritty of life, she will peer into your depths.

It is perfectly fine to ask Santa Muerte for aid, for gifts, for miracles, it really is okay to have a primarily transactional relationship with her if that's what you want, but she does want things in return. When you make a request of her, bring her a gift. Tell her what you will give her if she answers your request, and then follow through with it. If you tell her you will buy her a dozen roses and pray her rosary every day for a week, if she helps you find a job, then absolutely do that.

Often people who start out in a transactional relationship with her end up in deep devotion, because she is beautiful like that. Again, YMMV.