your level really doesn't matter for crucible(unless Iron Banner event is up as you lvl/gear/weapons aren't level restraint like the normal crucible) if you don't get the expansion pack the highest lvl you can go to is 31 and you can do the Venus raid; requirements is that you at least need to be a lvl 23 to participate and 6 people(although many people will want you to be 26+ in order to play
.With the expansion pack you can reach light lvl 32 as the only way to get to 32 is getting gear from the latest raid gear; "Crota's End" (however if the Iron Banner event is up you can buy raid lvl equivalent gear and equipping an exotic armor piece makes that you don't have to have a complete set of raid gear to reach lvl 32) you atleast need to be a lvl 27 in order to participate although again people will want atleast lvl 29 to even be helpful and again you need 6 people, however unlike the Venus raid it is possible to do this raid solo tough it take a high amount of skill.(or cheesing....)
for the crucible; what you should focus on it obtaining weapons; mostly of the legendary/exotic level as some they come with amazing perks and usually give you an edge in combat.(although certain rare weapons are good also.
what you should focus on is:
1st: continue do vanguard strikes in hope of getting better weapons and gear
2nd: earn vanguard points so that you can buy legendary gear/weapons
3rd: make sure to collect Strange Coins/Motes of Light so every friday-sunday an NPC by the name of Xur - Agent of the nine will sell exotic armor and weapons.
EDIT: I see you made this on the Sony board if you have the PS4 version hit me up, my PSN is in my sig
