First, a few dates to remember:
April 17th - Mars begins its two month retrograde starting in Sagittarius, where it will then dip back into Scorpio from May 27th-June 29th.
Second, keep in mind that planetary retrogrades mean to review, revisit...to slooooow down.
Third, know that Mars (action, anger, willpower, machines, sex, physical movement) going retrograde means that it will not be an optimal time for us to move full steam ahead with guns blazing where it pertains to new projects, ventures, and in some cases, sexual relationships. As doing so, we may experience significant delays, unnecessary recklessness and mistakes, losing fights or arguments, and a general lack of motivation. In the case of sexual relationships, Mars retrograde could deliver sexual chemistry or romantic connections that are DOA. Incidentally, Mars retrograde is also not a good time to undergo surgery, if it's something you have power over scheduling, as you'll want your surgeon (and their tools) to be sharp and on point.
In Sagittarius, Mars retro will be about scaling back on overindulging (especially of the physical sort) and reviewing where we may be overextending ourselves, or getting carried away with passions or projects that offer no real reward or accomplishment. With Sagittarius influenced energy, we can get so carried away with talk and ideas that action and follow-through suffers (or never even happens). Mars in Sagittarius, is also about being passionate about our beliefs and the actions we take to defend them. As Mars retrogrades in Sag, we're also going to be asked to reconsider the validity of those beliefs and whether or not they're worth fighting (and in some cases, dying) for. For example, religious zealotry is a shadowy quality of this Mars placement.
In Scorpio, Mars retro will be about power, where we may be abusing it (manipulation) and where we may be giving it willingly away. In cases where we may have been victimized by another (sexual abuse comes up in particular), Mars retro in Scorpio could offer the opportunity to reclaim our power from our abuser and heal our wounds. Since Mars is at home in the emotionally intense waters of Scorpio, Mars retro will also mean reassessing where we may be obsessed with controlling an outcome, the the actions of another person, or forcing something that isn't meant to be. Part of Mars in Scorpio's power is intuitive/gut instinct. As a result, we may need to review where we've been ignoring our instincts or intuition and how doing so never works in our favor.
All that being said, I like to think of Mars retrograde as our time to think first, shoot later; where we need to go back to the drawing board.