I am not too sure how to reply to you. Flippantly, I would wonder why you want to play a hobby that you seemed convinced you are "rubbish" at and that you say you have no natural inclination for?
A far better response, though, might be........
1) RPG's are not competitive. They are group storytelling, presented, focused and enabled by the GM. If your past/current experience with your tabletop gaming friend is competitive then you are probably wargaming not playing an RPG.
2) A strategic brain certainly comes in useful, but just knowing something of the mileu you are playing in ( Trek, Star Wars, DnD etc) and carefully listening to what the GM is saying (whether as an NPC, or in describing a setting) will help you to understand your options and hopefully pick a productive path. Having said that though, success isn't constant nor even always preferable. ("Failure" can sometimes be more fun as you struggle to get outta the mess and back on track). Remember this is a story not a competition.
3) Die rolling is not controlled by you - it is pure luck. ( assuming you just roll and don't try to manipulate the dice!!). I had one long term player who, for four games out of five, rolled brilliant dice, but on the fifth game his rolls were atrocious. And other players who had both good and bad in each game. It is just luck.
My advice is try to find a GM and players who are willing to help a novice, and just go have fun